Synthesis and hydrolysis of monocarbamate from allylic 1,4-dicarbamate: Bis-homodichloroinositol

The synthesis of novel bis-homodichloroinositol with a configuration similar to that of conduritol-D is reported for the first time. The photooxygenation of cis-dichloro-diene obtained using cyclooctatetraene as the starting molecule afforted the tricyclic endoperoxide. The reduction of the endoperoxide with thiourea gave the corresponding allylic cis-diol. Formation of the bis-carbamate groups with p-TsNCO of allylic cis-diol followed by the [(dba)₃Pd₂CHCl₃] in the presence of trimethylsilyl azide, gave a new monocarbamate as well as oxazolidinone derivative. Oxidation of the double bond in the monocarbamate with osmium tetraoxide followed by acetylation furnished the desired monocarbamate triacetate. Eventually, the desired halogenated bicyclo[4.2.0] inositol (bis-homodichloroinositol) were obtained in high yield by hydrolysis of the acetate groups and monocarbanate group by potassium carbonate in methanol. Characterization of all the synthesized compounds were performed by FT-IR, ¹H NMR, ¹³C NMR, COSY (2D-NMR), HRMS, and Elemental Analysis techniques.

Stereoselective synthesis of novel bis-homoinositols with bicyclo[4.2.0]octane motifs

Starting from cyclooctatetraene, bis-homoconduritols with cis-inositol and allo-inositol (or bicyclo[4.2.0]octane motif) structures were synthesized. Photooxygenation of trans-7,8-dibromo-bicyclo[4.2.0]octa-2,4-diene allowed the preparation of tricyclic endoperoxide. The compound diacetate was obtained by reduction of endoperoxide with thiourea followed by acetylation reaction. Removal of halides with zinc dust in acetic acid yielded the dien-diacetate, a key compound of the designed molecules. OsO₄ oxidation of diendiacetate followed by acetylation gave the corresponding hexaacetates. Finally, the novel desired bis-homoinositols were obtained in high yield by the ammonolysis of acetate groups. The structures of all synthesized compounds were characterized by spectroscopic methods.

Concise syntheses and some biological activities of dl-2,5-di-O-methyl-chiro-inositol, dl-1,4-di-O-methyl-scyllo-inositol, and dl-1,6-dibromo-1,6-dideoxy-2,5-di-O-methyl-chiro-inositol

The regio- and stereospecific synthesis of O-methyl-chiro-inositols and O-methyl-scyllo-inositol was achieved, starting from p-benzoquinone. After preparing dimethoxy conduritol-B as a key compound, regiospecific bromination of the alkene moiety of dimethoxy conduritol-B and acid-catalyzed ring opening of dimethoxydiacetate conduritol-B epoxide with Ac₂ O afforded the desired new chiro-inositol derivatives and scyllo-inositol derivative, respectively. Spectroscopic methods were employed for the characterization of all synthesized compounds. The novel inositols (11-17) had effective inhibition profiles against human carbonic anhydrase isoenzymes I and II (hCA I and II) and acetylcholinesterase (AChE). The novel inositols 11-17 were found to be effective inhibitors against AChE, hCA I, and hCA II enzymes. K_i values were calculated in the range of 87.59 ± 7.011 to 237.95 ± 17.75 μM for hCA I, 65.08 ± 12.39 to 538.98 ± 61.26 μM for hCA II, and 193.28 ± 43.13 to 765.08 ± 209.77 μM for AChE, respectively. Also, due to the inhibitory effects of the novel inositols 11-17 against the tested enzymes, these novel inositols are potential drug candidates to treat some diseases such as glaucoma, epilepsy, leukemia, and Alzheimer's disease.

Stereospecific Synthesis of 1,4-di-O-methyl-myo-inositol (liriodendritol)

1,4-di- O-methyl- myo-inositol, a natural product, was synthesised starting from p-benzoquinone. The treatment of 5,6-dibromocyclohex-2-ene-1,4-diol with Na/ROH-system afforded a C2-symmetric conduritol-B derivative key intermediate followed by acetylation. The OsO4 oxidation and followed by acetylation gave the tetraacetates. The hydrolysis of the acetate groups furnished the desired the myo-inositol derivatives in high yield.

Rhodium-catalysed Nucleophilic Ring Opening Reaction of 1- and 3-ethoxy-5,8-epoxy-5,8-dihydroisoquinolines

2-Ethoxy-3- and 5-chloropyridines were obtained from 2,3- and 2,5-dichloropyridine. Reaction of 2,3- and 2,5-dichlo-ropyridines with tBuLi in the presence of furan gave 1- and 3-ethoxy-5,8-epoxy-5,8-dihydroisoquinolines. The rhodium-catalysed ring-opening reaction of 1- and 3-ethoxy-5,8-epoxy-5,8-dihydroisoquinolines with 2-bromophenol furnished the isomer 7-(2-bromophenoxy)-1-ethoxy-7,8-dihydroisoquinolin-8-ol, 6-(2-bromophenoxy)-1-ethoxy-5,6-dihydroisoquinolin-5-ol and 7-(2-bromophenoxy)-3-ethoxy-7,8-dihydroisoquinolin-8-ol, 6-(2-bromophenoxy)-3-ethoxy-5,6-dihydroisoquinolin-5-ol respectively.

Synthesis of Anti–-anti (anti–-syn)-3,4:8,9-Tetraacetoxy-11-Oxa-Tricyclo [4.4.1.01,6]Undecanes

Synthesis of anti–-anti- and anti–-syn-3,4:8,9-tetraacetoxy-11-oxa-tricyclo[4.4.1.01,6] undecanes have been achieved starting from naphthalene. The Birch reduction of naphthalene gave 1,4,5,8-tetrahydro-naphthalene in high yield. 1,4,5,8-Tetrahydro-naphthalene was selectively oxidised with mCPBA to give 11-oxa-tricyclo[4.4.1.01,6]undeca-3,8-diene. OsO4 oxidation followed by acetylation furnished the corresponding tetraacetates.

Synthesis of a new class of aminocyclitol analogues with the conduramine D-2 configuration

A new class of aminocyclitol derivatives with the bicyclo[4.2.0]octane skeleton was synthesized starting from cyclooctatetraene. Photooxygenation of trans-7,8-diacetoxy- and cis-7,8-dichlorobicyclo[4.2.0]octa-2,4-diene afforded the bicyclic endoperoxides. Reduction of the latter with thiourea followed by a Pd(0) catalyzed ionization/cyclization reaction gave the corresponding oxazolidinone derivatives. Oxidation of the double bond with KMnO₄ or OsO₄ followed by acetylation gave the acetate derivatives, the exact configuration of which was determined by spectroscopic methods. Hydrolysis of the oxazolidinone rings and removal of the acetate groups furnished the desired aminocyclitols.

A Novel and Stereospecific Synthesis of Aminocyclitol: N-Tosyldihydroconduramine E2

A stereospecific synthesis of N-tosyldihydroconduramine E2, a new aminocyclitol, has been synthesised starting from cyclohexa-1,3-diene. The photooxygenation of cyclohexa-1,3-diene afforded the bicyclic endoperoxide. Reduction of the endoperoxide with thiourea and then reaction of the bis-carbamate with p-TsNCO followed by a palladium-catalysed ionisation/cyclisation reaction, gave a vinyl oxazolidin-2-one. Oxidation of the double bond in the oxazolidin-2-one with KMnO4 followed by acetylation, gave the oxazolidinone-diacetates. Hydrolysis of the oxazolidinone ring and removal of the acetate groups gave the desired aminocyclitol, N-tosyldihydroconduramine E2.

Synthesis and Characterisation of 2,3,4a,6,8a-penta-acetoxy decahydronaphthalene from 1,2,3,4-tetrahydronaphthalen-2-ol

2,3,4a,6,8a-Penta-acetoxy decahydronaphthalene has been synthesised starting from 1,2,3,4-tetrahydronaphthalen-2-ol. The Birch reduction of 1,2,3,4-tetrahydronaphthalen-2-ol gave a high yield of 1,2,3,4,5,8-hexahydronaphthalen-2-ol which was acetylated. The OsO4 oxidation of the 1,2,3,4,5,8-hexahydronaphthalen-2-yl acetate followed by further acetylation gave the pentaacetates.

Synthesis and Characterisation of 2,3a,5,6,7a-pentaacetoxy-octahydro-1H-indene from indan-2-ol

A synthesis of 2,3a,5,6,7a-pentaacetoxyoctahydro-1 H-indene has been achieved starting from indan-2-ol. The Birch reduction of indan-2-ol gave 4,7-dihydro-2-indanol in high yield which when followed by acetylation, resulted in the corresponding acetates. The OsO4 oxidation of the 2-acetoxy-4,7-dihydroindane followed by acetylation furnished the desired pentaacetates in high yield.

Regio- and stereospecific synthesis of a new benzoconduritol-C derivative

A stereospecific synthesis of 3-(2-bromophenoxy)-1,2,3,4-tetrahydronaphthalen-1,2,4-triol (benzoconduritol-C derivative) has been achieved by a fully regio- and stereospecific rhodium catalysed reaction of oxabenzonorbornadiene in the presence of 2-bromophenol.

(1SR,2SR,3SR,4RS,5RS,6RS,7SR,8RS)-7,8-Dichlorobicyclo[4.2.0]octa-2,3,4,5-tetrayl tetraacetate

In the title compound, C(16)H(20)Cl(2)O(8), the bicyclic system contains a central non-planar cyclohexane ring which is fused to a cyclobutane moiety. The cyclohexane ring has a chair conformation and the whole system adopts a syn conformation. The structure provides information on the stereochemical course of the chlorination, photo-oxidation and hydroxylation steps of the reaction.

Stereospecific synthesis of a new class of compounds: bis-homoconduritol-A, -D, and -F

Bis-homoconduritol derivatives with conduritol-A, -D, and -F structures have been synthesized starting from cyclooctatetraene. The photooxygenation of trans-7,8-dibromo- and cis-7,8-dichlorobicyclo[4.2.0]octa-2,4-dienes afforded the bicyclic endoperoxides. Reduction of the endoperoxides with thiourea followed by acetylation gave the corresponding diacetates. The KMnO(4) oxidation and epoxidation of the diacetates followed by acetylation gave the tetraacetates. Removal of the halides either with zinc-dust or Na-anthracene followed by the ammonolysis of tetraacetates afforded the bis-homoconduritol derivatives in high yield.