Quantitative Evaluation of the Reactivity of Alkylating Agents

A sensitive and reproducible method for quantitative evaluation of the relative reactivities of alkylating agents was developed, based on competitve alkylation. The method is superior to the known colorimetric methods. The reactivities of the agents could also be correlated with the 13C chemical shifts of the α-methylene. The method was successfully applied for the ranking of "soft" alkylating agents of low reactivity.

Improving the oral efficacy of CNS drug candidates: discovery of highly orally efficacious piperidinyl piperidine M2 muscarinic receptor antagonists

In search of a backup M(2) muscarinic receptor antagonist to the previously reported compound 1, we discovered compound (+)-14, which showed superior oral efficacy in animal models. The improvement of oral efficacy was achieved by modulating both the molecular weight and lipophilicity of the lead compounds.

The active site of a zinc-dependent metalloproteinase influences the computed pK(a) of ligands coordinated to the catalytic zinc ion

TNF-alpha converting enzyme (TACE) is a multidomain, membrane-anchored protein that includes a Zn-dependent protease domain. It releases the soluble form of cytokine tumor necrosis factor-alpha (TNF-alpha) from its membrane-bound precursor. TACE is a metalloprotease containing a catalytic glutamic acid, Glu-406, and a Zn(2+) ion ligated to three imidazoles. The protonation states of the active site glutamic acid and inhibitors are important factors in understanding the potency of inhibitors with acidic zinc-ligating groups such as hydroxamic and carboxylic acids. Density functional methods were utilized to compute pK(a) values using a model of the catalytic site of TACE and to predict a concomitant mechanism of binding, consistent with lowering the pK(a) of the bound ligand and raising the pK(a) of the active site Glu-406. Weak acids, such as hydroxamic acids, bind in their neutral form and then transfer an acidic proton to Glu-406. Stronger acids, such as carboxylic acids, bind in their anionic form and require preprotonation of Glu-406. Similar binding events would be expected for other zinc-dependent proteases.

Metabolic stabilization of benzylidene ketal M(2) muscarinic receptor antagonists via halonaphthoic acid substitution

The potential toxicological liabilities of the M(2) muscarinic antagonist 1 were addressed by replacing the methylenedioxyphenyl moiety with a p-methoxyphenyl group, resulting in M(2) selective compounds such as 3. Several halogenated naphthamide derivatives of 3 were studied in order to improve the pharmacokinetic profile via blockage of oxidative metabolism. Compound 4 demonstrated excellent M(2) affinity and selectivity, human microsomal stability, and oral bioavailability in rodents and primates.

Synthesis of C-11 methyl-substituted benzocycloheptapyridine inhibitors of farnesyl protein transferase

[formula: see text] Synthesis of C-11 methyl-substituted benzocycloheptylpyridine tricyclic compounds has been achieved via two different methods. Methylation of C-11 has been effected by treatment of amine 4 with BuLi followed by Mel quenching. In a similar procedure, introduction of a C-11 substituent with concomitant rearrangement of the exocyclic double bond has been carried out. Potent farnesyl protein transferase inhibitors have been synthesized using the above methodologies.

Conformational considerations in the design of dual antagonists of platelet-activating factor (PAF) and histamine

Following the discovery of the first dual antagonist of platelet-activating factor (PAF) and histamine, 1-acetyl-4-(8-chloro-5,6-dihydro-11H-benzo[5,6]cyclohepta[1,2-b]pyridin- 11-ylidene)piperidine, Sch 37370, 1, a related series of structures, exemplified by (+/-)-1-acetyl-4-(8-chloro-5,6-dihydro-11H-benzo[5,6]-cyclohepta[1,2-b] pyridin-11-yl)piperazine, Sch 40338, 2, were prepared. Interestingly, the compounds exhibited a parallel structure antiallergy activity relationship, suggesting that the two series may adopt a common conformation at the PAF receptor. Conformational analysis led to a proposal for this bioactive conformation accessible to both series. The synthesis of novel conformationally constrained analogues that might mimic the proposed bioactive conformation of these compounds, and the evaluation of their in vitro antiallergy activity form the subject matter of this report.

Dual antagonists of platelet activating factor and histamine. 3. Synthesis, biological activity and conformational implications of substituted N-acyl-bis-arylcycloheptapiperazines

A series of N-acyl-4-(5,6-dihydro-11H-benzo[5,6]cyclohepta[1,2-b]pyridin- 11-ylidene)piperazines is described that are dual antagonists of PAF and histamine. The structural requirements for activity in this series parallel those of their previously reported piperidinylidene counterparts. Whereas their global minimum energy conformations are different for both series of compounds, computer assisted molecular modeling suggests that a common bioactive conformation is possible.

Identification of novel farnesyl protein transferase inhibitors using three-dimensional database searching methods

Generation of a three-dimensional pharmacophore model (hypothesis) that correlates the biological activity of a series of farnesyl protein transferase (FPT) inhibitors, exemplified by the prototype 1-(4-pyridylacetyl)- 4-(8-chloro-5,6-dihydro-11H-benzo [5,6]cyclohepta[1,2-b]pyridin-11-ylidene)piperidine, Sch 44342, 1, with their chemical structure was accomplished using the three-dimensional quantitative structure-activity relationship (3D-QSAR) software program, Catalyst. On the basis of the in vitro FPT inhibitory activity of a training set of compounds, a five-feature hypothesis containing four hydrophobic and one hydrogen bond acceptor region was generated. Using this hypothesis as a three-dimensional query to search our corporate database identified 718 compounds (hits). Determination of the in vitro FPT inhibitory activity using available compounds from this "hitlist" identified five compounds, representing three structurally novel classes, that exhibited in vitro FPT inhibitory activity, IC50 < or = 5 microM. From these three classes, a series of substituted dihydrobenzothiophenes was selected for further structure-FPT inhibitory activity relationship studies. The results from these studies is discussed.

Sch 54445: a new polycyclic xanthone with highly potent antifungal activity produced by Actinoplanes sp

A novel antifungal agent, Sch 54445, was isolated from the fermentation broth of an Actinoplanes species. Sch 54445 was identified as a polycyclic xanthone related to the albofungin family of compounds on the basis of analyses of spectroscopic data. As a broad-spectrum antifungal agent, Sch 54445 exhibits highly potent activities against various yeasts and dermatophytes with MIC values approximately 0.00038 microgram/mL.

Antiulcer agents. 6. Analysis of the in vitro biochemical and in vivo gastric antisecretory activity of substituted imidazo[1,2-a]pyridines and related analogues using comparative molecular field analysis and hypothetical active site lattice methodologies

A number of substituted imidazo[1,2-a]pyridines and related analogues were selected for analysis of their in vitro biochemical and in vivo gastric antisecretory activity using comparative molecular field analysis (CoMFA) and hypothetical active site lattice (HASL) methodologies. The training set of compounds selected included those that were also chosen for an extensive molecular modeling study initiated, using the active analog approach, to define the pharmacophore by means of which 1 and its analogues interact with the gastric proton pump enzyme, H+/K(+)-ATPase. Using either CoMFA or HASL, it was possible to identify an optimal alignment paradigm of the proposed bioactive conformation for this series to reasonably predict the in vitro H+/K(+)-ATPase inhibitory potency in the purified enzyme model and the in vivo intravenous gastric antisecretory activity for compounds outside of the training set. Furthermore, the steric and electrostatic effects suggested by these two independent methods and their influence on determining biological activity were consistent and complementary to each other.

Antitumor 8-chlorobenzocycloheptapyridines: a new class of selective, nonpeptidic, nonsulfhydryl inhibitors of ras farnesylation

Ras farnesylation by farnesyl protein transferase (FPT) is an intracellular event that facilitates the membrane association of the ras protein and is involved in the signal transduction process. FPT inhibition could be a novel, noncytotoxic method of treating ras dependent tumor growth. We report here three structural classes of 8-chlorobenzocycloheptapyridines as novel, nonpeptidic, nonsulfhydryl FPT inhibitors having antitumor activity in mice when dosed orally. We discuss structural and conformational aspects of these compounds in relation to biological activities as well as a comparison to the conformation of a bound tetrapeptide FPT inhibitor.

An AM1 molecular orbital study of alpha-D-glucopyranose and beta-maltose: evaluation and implications

Chemical reactivity and other characteristics of alpha-D-glucopyranose and beta-maltose were evaluated within a semiempirical molecular orbital (AM1) framework. Theoretically generated structures compared well to those determined by X-ray crystallographic techniques. Calculations suggested that the secondary hydroxy functions (OH-2 and OH-3) of the mono- and di-saccharides were more acidic than the primary alcohol (OH-6), which is consistent with experimental findings. In addition, the enhanced reactivity of the OH-3 locus, which is observed upon OH-2 alkylation of the object sugars, was rationalized in terms of increased OH-3 acidity. The chemical behavior of the monomers examined may be insightful in explaining the reactivity of glucopyranose polymers.

Isobenzofurans as conformationally constrained miconazole analogues with improved antifungal potency

A series of halogen-substituted isobenzofuran analogues was synthesized, which represented conformationally constrained analogues of miconazole (1). In vitro and in vivo topical antifungal activity against both dermatophytes and Candida species varied widely, but 13c proved to be significantly superior to both 1 and clotrimazole against a vaginal Candida infection in hamsters, while 13b was significantly more active than 1 against a a topical Trichophyton infection in guinea pigs. None of the compounds were orally active. When the most direct analogue of 1 proved to be among the least active, a molecular modeling study was done using 1, the two active analogues 13b and 13c, and the inactive analogue 13a. All four compounds possessed skeletally similar conformations either at or energetically readily accessible from the global minimum energy conformations. This common conformation of the inactive analogue 13a, however, occupies unique molecular volume space associated with two chlorine atoms, which must also present unique electrostatic properties at the receptor. The conformation-activity relationships discussed may contribute toward deduction of additional structural requirements for pharmacophore optimization and more efficacious antifungal drugs.

New water-soluble pilocarpine derivatives with enhanced and sustained muscarinic activity

The synthesis of an homologous series of new water-soluble derivatives of pilocarpine is described. The new compounds, referred to as soft quaternary salts, are water soluble by virtue of a cationic ammonium head and their lipophilicity can be modulated by manipulating the size and the nature of the substituent in the inactive portion of the molecule. The miotic activity of the compounds was evaluated after administration to normotensive New Zealand White rabbits. Changes in pupil size indicated a substantial cholinergic effect on the iridal sphincter musculature. The best candidate, compound 20, which has a 16-carbon side chain, was evaluated for reduction of the intraocular pressure in genetically glaucomatous Beagles. Compound 20 is superior to pilocarpine in both tests, with a potency 10 to 20 times that of the parent compound and a longer duration of action. It is suggested that the new compounds are prodrug forms of pilocarpine which greatly enhance the corneal bioavailability of the parent compound.

Antiulcer agents. 5. Inhibition of gastric H+/K(+)-ATPase by substituted imidazo[1,2-a]pyridines and related analogues and its implication in modeling the high affinity potassium ion binding site of the gastric proton pump enzyme

A number of substituted imidazo[1,2-a]pyridines and related analogues were selected for biochemical characterization in vitro against both the purified gastric proton pump enzyme, H+/K(+)-ATPase, and the intact gastric gland. The inhibitory activity in these two in vitro models was then examined for correlation with the gastric antisecretory potency determined for these compounds in vivo by using the histamine-stimulated Heidenhain pouch dog. Analysis of the biological data suggested that the inhibitory activity of the analogues determined in two in vitro models is predictive of their in vivo gastric antisecretory activity following intravenous, but not oral, administration. Furthermore, the good correlation observed between the in vitro and in vivo models suggests that these compounds are gastric proton pump inhibitors in vivo. A molecular modeling study of these compounds using the active analogue approach has defined the molecular volume which is shared by the active analogues, as well as the molecular volume which is common to the inactive analogues. Graphical representation of the difference between these molecular volumes can be interpreted in terms of a hypothetical description of the pharmacophore by means of which 3-(cyanomethyl)-2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine, Sch 28080 (1) and its analogues interact with the gastric proton pump enzyme, H+/K(+)-ATPase.

Substituted 1,3-dihydro-2H-pyrrolo[2,3-b]pyridin-2-ones as potential antiinflammatory agents

A series of analogues based on the 1,3-dihydro-2H-pyrrolo[2,3-b]pyridin-2-one ring system have been synthesized and shown to possess oral antiinflammatory activity in both the reverse passive Arthus reaction (RPAR) pleural cavity assay in rats and in the adjuvant-induced arthritic rat model (AAR). Several members of this series additionally exhibit an inhibitory effect on the in vivo production of prostaglandin- and leukotriene-derived products or arachidonic acid metabolism although these compounds exhibit no significant inhibitory activity against the cyclooxygenase and 5-lipoxygenase enzymes in vitro. Structure-activity relationships in this series are discussed.

Antiulcer agents. 4. Conformational considerations and the antiulcer activity of substituted imidazo[1,2-a]pyridines and related analogues

Definition of the interrelationship between the conformational characteristics of a series of substituted imidazo[1,2-a]pyridines and their antiulcer activity was investigated by examining the conformational properties of 3-cyano-2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine (1), using a variety of experimental and theoretical methods. The results of these studies was the identification of two distinctly different candidates, designated the "folded" and the "extended" conformation, respectively, to represent the two possible minimum-energy conformations of 1. In order to select the biologically relevant conformer, a group of 3-substituted 2-methylimidazo[1,2-a]pyridines, having either a cis or a trans 2-phenylethenyl substituent at the 8-position were designed as conceptually simple and synthetically accessible semirigid analogues of the respective candidate conformers. Gastric antisecretory activity was found to reside only in the trans isomers (compounds 11, 15, and 17), which mimic the "extended" conformation. This observation led to the construction of 8,9-dihydro-2-methyl-9-phenyl-7H-imidazo[1,2-a]pyrano[2,3-c]pyridi ne-3- acetonitrile (40), a rigid tricyclic analogue that is effectively locked in the "extended" conformation and that exhibited an antiulcer profile comparable to that of prototype 1. These results unequivocally demonstrate that, in accord with expectation for a drug operating at a specific receptor, the conformational characteristics of the molecule have a substantial effect in determining its antiulcer activity. More precisely, it has been demonstrated that it is the "extended" conformation of 1 that represents the "bioactive" form of the drug. These results constitute the basis for a molecular probe that should aid in the investigation of the as yet uncharacterized gastric proton pump enzyme (H+/K+-ATPase), by means of which 1 and its analogues presumably exert their pharmacologic actions.

Antiinflammatory activity of a series of substituted 2,3-dihydro-6-hydroxypyrimido[2,1-f]purine-4,8(1H,9H)-diones

A series of substituted analogues based on the novel 2,3-dihydro-6-hydroxypyrimido[2,1-f]purine-4,8(1H,9H)-dione ring system have been synthesized and shown to exhibit antiinflammatory activity in the adjuvant-induced arthritis rat model (AAR). The activity exhibited by the pyrimidopurinediones in this model of chronic inflammation is comparable to that of their previously studied 2-oxo congeners, the 6-hydroxypyrimido[2,1-f]purine-2,4,8-(1H,3H,9H)-triones, the best of which show potency levels approximately equal to that of naproxen. On the basis of its potency in the AAR assay, 9-benzyl-2,3-dihydro-1,3-dimethyl-6-hydroxy-7-(3-methyl-2-butenyl) pyrimido-[2,1-f]purine-4,8(1H,9H)-dione was selected for further evaluation and found to exhibit cyclooxygenase inhibitory activity in the in vitro rat neutrophil model. With respect to side-effect liability, this prenylated derivative has been shown to be devoid of gastric ulcer inducing potential, as well as the ocular toxicity observed previously with the 2-oxo series.

Antiallergy agents. 1. Substituted 1,8-naphthyridin-2(1H)-ones as inhibitors of SRS-A release

A novel class of antiallergy agents, the substituted 1,8-naphthyridin-2(1H)-ones, is described. The present compounds are orally active, potent inhibitors of allergic and nonallergic bronchospasm in animal models. Structure-activity studies of the lead compound in this series, 1-phenyl-3-n-butyl-4-hydroxynaphthyridin-2(1H)-one (11), identified three compounds of interest, 1-phenyl-3-(2-propenyl)-4-acetoxy-1,8-naphthyridin-2(1H)-one (12), 1-(3'-chlorophenyl)-3-(2-propenyl)-4-acetoxy-1,8-naphthyridin-2(1H )-one (87), and 1-(3'-methoxyphenyl)-3-(2-propenyl)-4-acetoxy-1,8-naphthyridin-2(1 H)-one (89). The mechanism of antiallergy activity may involve inhibition of the release of the sulfidopeptide leukotrienes. 1-Phenyl-3-(2-propenyl)-4-acetoxy-1,8-naphthyridin-2(1H)-one, Sch 33303 (12), was selected for preclinical development as an antiallergy agent.

Antiulcer agents. 2. Gastric antisecretory, cytoprotective, and metabolic properties of substituted imidazo[1,2-a]pyridines and analogues

The search for a successor to 3-(cyanomethyl)-2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine, Sch 28080 (27), a compound that exhibits gastric antisecretory and cytoprotective properties and has undergone clinical evaluation as an antiulcer agent, has culminated in the identification of four related compounds that exhibit pharmacologic profiles similar to that of 27. In three of these potential successors an amino group functions as a surrogate for the 3-cyanomethyl substituent of the prototype. The present work concerns, in addition to an evaluation of the structure-activity relationships of a series of analogues of 27, preliminary studies of the pharmacodynamics and metabolism of 27, performed with the aid of cyano carbon labeled versions of the drug (13C labeled; 28; 14C labeled, 29). These studies have shown that 27 is well-absorbed and extensively metabolized and that the major metabolite of 27 is the thiocyanate anion. A similar study performed on 3-amino-2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine, labeled at the 3-position with carbon-13 (41) or carbon-14 (42), revealed that this compound, which has an antisecretory/cytoprotective profile comparable to that of 27, is also metabolized to thiocyanate anion, although this must occur via a different mechanism. The chemistry section includes a discussion of the potential sites of protonation of the pharmacologically similar 3-amino analogue 40 and the structurally related imidazo[1,2-a]pyrazine 67. Predictions based on charge density and protonation product stabilities are presented. That N1 is the site of protonation in these analogues has been definitively demonstrated by X-ray crystal structure analysis, which also unequivocally established the assigned imidazo[1,2-a]pyrazine ring structure.

Antiulcer agents. 3. Structure-activity-toxicity relationships of substituted imidazo[1,2-a]pyridines and a related imidazo[1,2-a]pyrazine

Investigation of the interrelationship between structure, antiulcer activity, and toxicology screening data derived from a series of compounds selected from structure-activity studies directed toward identifying a successor to 3-(cyanomethyl)-2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine, Sch 28080 (1), has identified 3-(cyanomethyl)-2,7-dimethyl-8-(phenylmethoxy)imidazo[1,2 -a]pyridine (5), 3-amino-2-methyl-8-(2-phenylethyl)imidazo[1,2-a]pyridine (6), and 3-amino-2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyrazine (7). These analogues exhibit a combination of antisecretory and cytoprotective activity in animal models, while eliminating the adverse effects of the prototype 1. One of these, 3-amino-2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyrazine, Sch 32651 (7), has a profile meeting all criteria.

Antiinflammatory activity of substituted 6-hydroxypyrimido[2,1-f]purine-2,4,8(1H,3H,9H)-triones. Atypical nonsteroidal antiinflammatory agents

A novel class of antiinflammatory drugs, which are substituted derivatives of the fused tricyclic system 6-hydroxypyrimido[2,1-f]purine-2,4,8(1H,3H,9H)-trione, is described. Synthetic procedures and structure determination with the assistance of X-ray crystallography are discussed. Semiempirical molecular orbital calculations are used to investigate the relative stability of the possible isomers and tautomers of the title compounds. A biological profile of the class, and of several of the more potent analogues, in several antiinflammatory models, including the adjuvant-induced arthritis and the collagen II models, is defined. Several members of the class are shown to possess extremely low ulcerogenic effects in spite of exhibiting cyclooxygenase inhibition. A preliminary bioavailability study of two of the lead structures is presented. The compounds 6-72 appear to constitute a class of drugs that shows interesting potential antiarthritic activity and also exhibits an activity profile different from that of the standard classical NSAI drugs, as determined by a comparison of the profile of this class of drug with that of several standard agents. Certain findings from toxicological studies have precluded the further development of compounds within this group, although related structural types are being investigated.

Antiulcer agents. 1. Gastric antisecretory and cytoprotective properties of substituted imidazo[1,2-a]pyridines

A novel class of antiulcer agents, the substituted imidazo[1,2-a]pyridines, is described. The present compounds are not histamine (H2) receptor antagonists nor are they prostaglandin analogues, yet they exhibit both gastric antisecretory and cytoprotective properties. The mechanism of gastric antisecretory activity may involve inhibition of the H+/K+-ATPase enzyme. Structure-activity studies led to the identification of 3-(cyanomethyl)-2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine, SCH 28080 (27), which was selected for further development and clinical evaluation.

Stereochemical considerations and the antiinflammatory activity of 6-amino-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ols and related derivatives

The antiinflammatory activity of a series of 6-amino-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ols and related derivatives was examined using the reverse passive Arthus reaction (RPAR). The antiinflammatory activity of these compounds was markedly influenced by the stereochemistry of the amino alcohol moiety. The threo diastereomer exhibited activity in the RPAR, while the erythro diastereomer was devoid of any significant antiinflammatory activity. The antiinflammatory activity of the amino alcohols was also significantly influenced by the position and nature of the aromatic substituent. Latentiation of the amino alcohol function resulted in analogues exhibiting antiinflammatory activity equivalent to their amino alcohol precursors. Masking the amino alcohol function as a more stable derivative led to analogues exhibiting an antiinflammatory profile unique to their structural class.

N-hydroxymethyl derivatives of nitrogen heterocycles as possible prodrugs I: N-hydroxymethylation of uracils

Solid samples of 1,3-dihydroxymethyluracil, 3-hydroxymethyl-1-methyluracil, and 1-hydroxymethyl-3-methyluracil were prepared, and their structures were confirmed by spectroscopic analysis. The thermodynamics and kinetics of the formation of N-hydroxymethylated uracils in aqueous formaldehyde solutions also were studied. The equilibrium constants for formation of N-1-hydroxymethyl derivatives were approximately twice those for formation of N-3-hydroxymethyl derivatives, and they were formed more rapidly throughout the pH 3--8 range. Substituents at C-5 of uracil had little effect on the thermodynamics of N-hydroxymethylation. The potential usefulness of N-hydroxymethyl compounds as prodrugs is discussed.

Improved delivery through biological membranes VIII: Design, synthesis, and in vivo testing of true prodrugs of aspirin

Novel activated ester-type prodrugs of aspirin were designed and synthesized. The methylthiomethyl, methylsulfinymethyl, and methylsulfonylmethyl esters of aspirin (acetylsalicylic acid) were cleaved in vitro in plasma to form aspirin rather than the corresponding salicylates. In vitro studies using dogs indicated that at least one aspirin derivative, methylsulfinylmethyl-2-acetoxybenzoate, is a true aspirin prodrug since aspirin was detected in the blood after prodrug administration.

Soft drugs. 1. Labile quaternary ammonium salts as soft antimicrobials

Strategies for the design of safer drugs are discussed. The various classes of "soft drugs" are designed to avoid undesired metabolic disposition (primarily various oxidative routes, occurring via possible toxic intermediates) and to be metabolized by a predictable manner with controlled rates. As a first example for the "soft analogue" type drugs, a new class of antimicrobial, surface-active quaternary salts of the type RCOOCHR1--N+ comes from X- was developed. These "soft" quaternary salts are isosteric analogues of known "hard" quaternary surfactants and are characterized by predictable and controllable cleavage (metabolism) to nontoxic components, while showing good activity against a wide range of bacteria. Due to their soft nature (low toxicity), the new antimicrobials are much safer than the conventional, hard analogues.

Soft drugs. 3. A new class of anticholinergic agents

A new class of antimuscarinic drugs was designed and synthesized. The compounds are "soft" quaternary ammonium esters in which there is only one carbon atom separating the ester oxygen and the quaternary head. The compounds are potent anticholinergics when derived from hindered "umbrella" acids and cholinergics when derivatives of simple aliphatic acids. The more potent anticholinergics have up to 10 times higher acetylcholine antagonist activity than atropine, but they have a much shorter duration of action. The compounds cleave hydrolytically with simultaneous destruction of the quaternary head. The compounds are promising as selective, local agents, particularly as inhibitors of eccrine sweating.

Soft drugs. 2. Soft alkylating compounds as potential antitumor agents

A class of soft alkylating compounds as potential anticancer agents was developed. The first examples include alpha-halo esters of various carboxylic acids. A new method for quantitative evaluation of the alkylating reactivity was developed, using a competitive alkylation reactivity was developed, using a competitive alkylation reaction, followed by NMR analysis of the reaction mixture. The method is sensitive and reproducible. One of the two selected soft alkylating agents, chloromethyl hexanoate, was found to have anticancer activity.

Formation of a thio analog of noracronine

Acronine was heated with tetraphosphorus decasulfide in benzene to give a mixture of products, the major component (A) being identified tentatively as an unstable product derived from four molecules of noracronine with one molecule of tetraphosphorus decasulfide. Treatment of Compound A with various solvents and heat converted it into a maroon solid (B), which was shown to be 7-thionoracronine.