[Synthesis of enantiomerically pure 6,10-epoxybenzocycloocten-7-amines with CNS activity]

Brønsted Acid-Promoted Cyclodimerization of Indolyl Ketones: Construction of Indole Fused-Oxabicyclo[3.3.1]nonane and -Cyclooctatetraene Ring Systems

A Brønsted acid-promoted cyclodimerization of C(3)-, C(2)-, or N(1)-substituted indole ketone derivatives is described. A wide range of structurally diverse bisindole fused-9-oxabicyclo[3.3.1]nonane and bisindole fused-cyclooctatetraene (COT) derivatives can be prepared in good to high yields with high efficiency.

Construction of Complex Bisether-Bridged Medium-Sized Cyclic Compounds from o-(1-(Acyloxy)propargyl)benzaldehydes under Base and Acid Catalysis

We report herein our serendipitous discovery of the rapid and straightforward accesses to unprecedented diverse complex molecular structures from readily available starting materials. Catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene under mild conditions, o-(1-(acyloxy)propargyl)benzaldehydes 1 underwent efficient and selective dimerization reactions to produce novel complex bisether-bridged tricyclic products 3 and 4. The reactions proceeded most probably through dimerizations between 3-methylene-3H-isochromene intermediate and its zwitterionic resonance structures which were generated from a concerted 6-π electrocyclic ring closure reaction from the initially formed (2-formylphenyl)allene intermediates derived directly from o-(1-(acyloxy)propargyl)benzaldehydes. Treatment of the resulting product simply with NaOEt in ethanol and aqueous HCl, respectively, enabled further development of complex molecular diversities.

Au(I)-catalyzed synthesis of 8-oxabicyclo[3.2.1]oct-2-enes and 9-oxabicyclo[3.3.1]nona-2,6-dienes from enynol via oxonium/Prins-type cyclization

A sustainable and simple Au(I) catalytic system to synthesise 8-oxabicyclo[3.2.1]oct-2-enes and 9-oxabicyclo[3.3.1]nona-2,6-dienes from enynol via oxonium/Prins-type cyclization is described. The key advantages of this reaction are selectivity, good functional group tolerance and a new approach for synthesis of oxabicyclic and oxatricyclic systems.

Asymmetric synthesis and enantiospecificity of binding of 2-(1,2,3,4-tetrahydro-1-isoquinolyl)-ethanol derivatives to mu and kappa receptors

A number of 2-(1,2,3,4-tetrahydro-1-isoquinolyl)-ethanol derivatives 7a-e have been synthesized in diastereomerically and enantiomerically pure form and have been evaluated for their binding affinity at mu and kappa opioid receptors. The amido ketones 5a-c and ent-5a-c, which were accessible by employing 3b and ent-3b for Asymmetric Electrophilic Amidoalkylation reactions, served as starting compounds. Upon reduction of 5a-c and ent-5a-c the amido alcohols l-6a-c, u-6a-c, ent-l-6a-c and ent-u-6a-c were obtained. Hydrolysis of these compounds yielded the secondary amino alcohols l-7a-c, u-7a-c, ent-l-7a-c and ent-u-7a-c and upon reductive methylation of l-7b-c, u-7b-c, ent-l-7b-c and ent-u-7b-c with CH2O and NaCNBH3 the tertiary amino alcohols l-7d-e, u-7d-e, ent-l-7d-e and ent-u-7d-e were obtained. The binding affinities of the final compounds l-7a-e, u-7a-e, ent-l-7a-e and ent-u-7a-e at both the mu and the kappa receptor were strongly dependent on their stereochemistry. In each case isomers exhibited higher affinity at the mu than at the kappa receptor. For the secondary amino alcohols 7a-c the affinity at the mu receptor followed the stereochemical order l-7 > ent-l-7 > ent-u-7 > u-7 whereas for the tertiary amino alcohols the order l-7 > u-7 > ent-l-7 > ent-u-7 was found. The stereoisomers l-7d and l-7e of the tertiary amino alcohols were found to be the most active compounds the latter exhibiting a Ki value of 7.17 which is close to that of Morphine (Ki = 1.64). In an in vivo model, the Writhing Test, both compounds l-7d and l-7e displayed high analgetic activity.

Tricyclic CNS active agents by intramolecular Oxa-Pictet-Spengler reaction

Mitsunobu inversion of the (S)-configurated lactate (S)-7, which is prepared in four steps starting from (S)-tyrosine, leads to the (R)-configurated lactate (R)-7. The key step in the transformation of the enantiomeric lactates (S)-7 and (R)-7 into the benzomorphan analogous tricycles (R,S)-16a,b, (S,R)-16a,b, (S,S)-22, and (R,R)-22 is an intramolecular Oxa-Pictet-Spengler reaction: The amides (S)-13, (R)-13, (S)-19 and (R)-19, in which the carbonyl moiety-masked as an acetal-is linked to the 2-phenylethanol moiety, are cyclized to give the tricyclic amides (R,S)-15, (S,R)-15, (S,S)-21, and (R,R)-21, respectively. In a concentration of 100 microM both enantiomers of 16a, 16b, and 22 are not able to compete with 3H-(+)-MK 801 for the phencyclidine binding sites of NMDA receptors. In vivo, only (R,S)-16b and (S,S)-22 exhibit weak sedative and analgesic activity.

[CNS-active pyrans: amine- and aryl- substituted dioxabicyclooctanes]

The amin- and phenyl substituted 6,8-dioxabicyclooctanes 10 and 11 show distinct CNS-activities. Intensity and profile depend on the type of amine and the stereochemistry of the products. Therefore, we have synthesized 6,8-dioxabicyclooctanes with different amine-phenyl distances and examined their CNS-activities on mice as well as by receptor binding studies with the PCP-binding site which is part of the NMDA-receptor-complex.

[Synthesis of homochiral 5,9-epoxybenzocyclooctenes with amino substitutents: relationship between structure and CNS activity]

This paper deals with the synthesis and psychopharmacological effects of variations of the sedative and analgesic tricyclic amines 3a and 3b: Starting with the homochiral ketone 4 the amines 5 (primary amino group in equatorial position), 7 (axially oriented dimethylamino group), 9 (additional phenyl residue in position 7), 13b, and 14b (equatorially and axially arranged dimethylaminomethyl group) and 23 and 24 (axial amino group shifted to position 9) are prepared. BBr3 cleaves the phenolic ethers of the secondary amine (+/-)-3a to yield the aminodiphenol (+/-)-10. -Keeping mice under observation for behavioral anomalies (Irwin screen) and analgesic activity (writhing test) shows, that the amines 5, 7, 9, (+/-)-10, 13b, 14b, and 23 do not reach the sedative and analgesic effects of the amines 3a and 3b, described by us.

[2,6-Epoxy-3-benzazocines: centrally acting N/O-acetals produced by cyclization of amino- and amidoacetals]

Under acidic conditions the secondary amines 10a and 10b, the primary amine 15, the amide 17a, and the urethane 17b were cyclized to yield the 2,6-epoxy-3-benzazocines 11a, 11b, 16, 18a and 18b, respectively. Ring closure of the inverse amide 5a, however, failed to give the tricyclic N/O-acetal 6. With LiAlH4 the epoxy bridge of the urethane 18b was opened to afford the bicyclic 3-benzazocine 20. While the N-(2-methoxyethyl) derivative 11b did not influence the behaviour of mice, the N-methyl derivative 11a showed strong central effects.

[Benzomorphan analogs with doxpicomine partial structure: synthesis andpsychopharmacologic investigations of 5-aminomethyl- and 5-(alpha-aminobenzyl)- substituted 2,6-epoxy-3-benzoxocines]

Addition of the beta-alanine derivative 6 to the homophthalaldehyde monoacetal 5 and subsequent LiAlH4-reduction led to the dihydroxy acetal 8, which was cyclized with acid to give the 5-aminomethyl-2,6-epoxy-3-benzoxocines 2a and 2b. The reaction of 5 with the anion of the beta-lactam 9 yielded two separable diastereomers: 10a with u,l-configuration and 10b with 1,1-configuration. Via the 2-benzopyran 11a (11b), the aminoalcohol 12a (12b), and the secondary amine 13a (13b), the beta-lactam adduct 10a (10b) was transformed to give the 5-(alpha-dimethylaminobenzyl)-2,6-epoxy-3-benzoxocine 3d (3b). The relative configurations of all these "beta-lactam route" products (10-13, 3d, and 3b) were established by their 1H-NMR-spectra. Attempts failed to get the missing diastereomers 3a and 3c by epimerization of the beta-lactams 11a and 11b or by reductive amination of the benzoyl derivatives 17a and 17b. Finally, 3a and 3c were obtained by phenylmagnesium bromide addition to the nitriles 21a and 21b, followed by LiAlH4-reduction, formaldehyde/NaBH3CN methylation and chromatographic separation. In the Irwin-screen (mouse) only 2a.HCl, 3b, and 3d (100 mg/kg body weight) caused weak central effects.