Synthetic study of optically active 3-azabicyclo[3.3.0]octane-2,6,8-tricarboxylic acid

Synthesis of (1R,2S,5S,6R,8S)-3-azabicyclo[3.3.0]octane-2,6,8-tricarboxylic acid (2) from trans-4-hydroxy-L-proline (5) was attempted. A Diels-Alder reaction of 3,4-dehydroproline derivative 9 and cyclopentadiene afforded a single stereoisomer 11. The Diels-Alder adduct was smoothly converted to the hydrochloride of 2 (24) via RuO(4) oxidation. Although some racemization of the material or product was observed during the synthetic processes, the amino acid 24 proved to be optically pure.     

Synthesis of unnatural amino acids: (S,S,S)-2-azabicyclo[3.3.0]octane-3-carboxylic acid

(S,S,S)-2-Azabicyclo[3.3.0]octane-3-carboxylic acid 1, a structural element of the very potent ACE inhibitor HOE 498, is readily available via a diastereo selective synthesis starting from serine or cystine.     

Synthesis of 2-monofunctionalized 2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-diones

New (1R*,5S*)-2-R-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-diones containing the terminal carboxy or hydroxy group in the substituent R were synthesized by cyclocondensation of 4,5-dihydroxyimidazolidin-2-one with 1-R-ureas. Single-crystal X-ray diffraction analysis showed that 2-carboxyethyl-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione crystallizes as a racemate.     

Synthesis of 1-azabicyclo[3.3.0]octane derivatives and their effects as piracetam-like nootropics

A useful pharmaceutical intermediate, 5-nitromethyl-1-azabicyclo[3.3.0]octane (1), was prepared in one step from 1,7-dichloro-4-heptanone (4) under mild conditions. Catalytic hydrogenation of 1 over Raney Ni in the presence of sodium hydroxide afforded 5-aminomethyl-1-azabicyclo[3.3.0]octane (2) in high yield. Piracetam analogues 20-23, which were pyrrolidine derivatives involving a 1-azabicyclo[3.3.0]octane ring, were synthesized. Pharmacological tests showed that N-[(1-azabicyclo[3.3.0]octan-5-yl)methyl]-2-oxo-1-pyrrolidineacetamid e (20) improves cerebral function.     

Synthesis of ethyl cis 2-[(Diethoxyphosphoryl)methyl]-7-oxo-3-phenyl-6-phthalimido-l-azabicyclo[3.2.0]hept-3-ene-2-carboxylate and Methyl cis-2-Bromo-3-methyl-8-oxo-7-phthalimido-4-oxa-1-azabicyclo[4.2.0]octane-2-carboxylate

The synthesis of a Δ¹-carbapenem and two β-lactams possessing a Br-atom at the N-substituting center not involved in the lactam ring and bearing the carboxyl group is described. The β-lactams having this kind of Br-substitution are more susceptible to nucleophilic attack than those having a conjugated double bond with the N-atom of the β-lactam ring. DBU is found to be an excellent reagent for the elimination of the silyloxy function. Moreover, a simple method for the addition of diethyl phosphite to an α, β-unsaturated double bond using a catalytic amount of NaH is described.     

N-Silylation of 2,4,6-Trialkyl-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-diones

N-Trimethylsilyl derivatives of 2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-diones have been prepared for the first time and the electrophilic substitution reaction of the trimethylsilyl group has been studied.     

Preparation of Bicyclo[3.3.0]octane-2,8-dione- and Declain-1,8-dione-Derivatives

Alkylation of bicyclo[3.3.0]octane-2,8-dione ( 1 ), which is prepared by a modification of the procedure described in the literature, gives the methyl- and propynyl-derivatives 6 and 7 (Scheme 1). In addition to the method described previously (Scheme 2), 9-methyl-cis-decalin-1,8-dione 9 is obtainable stereoselectively either by cyclization of keto-acid 16 , or by aldol cyclization of keto-aldehyde 26 and oxydation of the resulting alcohols 24 and 25 (Scheme 4). The β-keto-alcohols 24 and 25 undergo a base-catalyzed isomerization; the trans-decalin isomers 27 and 28 are not detected in this equilibrium mixture (Schemes 4 and 5)l. Monoreduction of cis-dione 9 gives the endo-alcohol 25 , while 27 is the favored product of the reductin of trans-dione 10 (Scheme 4). Optically pure (+)- 25 can be prepared from (9S,10R)-monoacetal 29 (Scheme 5).     

Synthesis of the 3-acetoxy-7-oxo-1-azabicyclo [3.2.0] hept-2-ene-2-carboxylate system

Lead tetraacetate oxidation of the carbapenem derived ethanethiol adducts (4–6) gave the corresponding 3-acetoxy-3-ethylthio derivatives (7–9). Oxidation to sulphone and elimination of ethylsulphinic acid furnished the 3-acetoxy-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate ester (12). Alternatively, elimination of acetic acid from (7) and (8) provided a new route to alkylthiocarbapenems.     

Successful synthesis of 2,4,6,8-tetraiodo-2,4,6,8tetraazabicyclo[3.3.0]octane-3,7-dione

Tomsk Polytechnical University. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1695–1696, December, 1995. Original article submitted November 27, 1995.     

E- or Z-selective Horner-Wittig reactions of substituted bicyclo[3.3.0]octane-3-ones with chiral phosphonoacetates

The Horner-Wittig reaction of substituted bicyclo[3.3.0]octane-3-ones with chiral phosphonoacetates 2 gave the corresponding unsaturated esters in $\text{E}$/$\text{Z}$-ratios of up to 91 : 9.     

Exploiting the regioselectivity of pyroglutamate alkylations for the synthesis of 6-azabicyclo[3.2.1]octanes and 4-azabicyclo[3.3.0]octanes

Depending on the N-protecting group of pyroglutamates, the reactivity can be directed to the formation of 6-azabicyclo[3.2.1]octanes or 4-azabicyclo[3.3.0]octanes, which are conformationally restricted glutamate analogues.     

Synthesis of enantiopure 3-azabicyclo[3.3.0]octen-7-one derivatives via intramolecular Pauson-Khand cycloaddition reaction using tri-O-acetyl-D-glucal as starting material

Some N-substituted-3-azabicyclo[3.3.0]octen-7-one derivatives have been synthesized in an enantiomerically pure form starting from tri-O-acetyl-D-glucal via intramolecular Pauson-Khand (IPK) cycloaddition.     

Acyl derivatives of 5-amino-2-azabicyclo[3.2.2]nonanes

5-Amino-2-azabicyclo[3.2.2]nonanes possess activity against the causative organisms of Human African trypanosomiasis and Malaria tropica. Their newly prepared N-acyl derivatives were inactive against Trypanosoma b. rhodesiense, but some of them showed good antiplasmodial activity against a multiresistant strain of Plasmodium falciparum. The results are compared to the activities of the N-unsubstituted compounds and N-sulfonyl analogues. The diastereomeric character of the formed amides was elucidated by NMR spectroscopy.