Stereoselective synthesis of cis and trans 2-substituted 1-phenyl-3-azabicyclo[3.1.0]hexanes

The Stereoselective synthesis of cis and trans 2-methyl-1-phenyl-3-azabicyclo[3.1.0]hexanes and 1,2-diphen-yl-3-azabicyclo[3.1.0]hexanes from 2-oxo-1-phenyl-3-azabicyclo[3.1.0]hexane is described. The relative stereochemistry of the products was established by nuclear magnetic resonance and molecular modeling studies.     

Novel synthesis of 3-azabicyclo[3.1.0]hexanes by unusual palladium(0)-catalyzed cyclopropanation of allenenes

Novel stereoselective synthesis of 3-azabicyclo[3.1.0]hexanes from allenenes is presented. Treatment of N-protected 4-alkyl-4-(N-allyl)amino allenes with allyl carbonate and a catalytic amount of Pd(2)(dba)(3).CHCl(3) in MeCN leads to stereoselective formation of the 3-azabicyclo[3.1.0]hexane framework in moderate to good yields. [reaction: see text]     

An efficient stereoselective synthesis of 1-iodo- or 1-phenyl selenenyl-2-aryl-3-azabicyclo[3.1.0]hexane via electrophilic cyclization of benzyl-2-arylmethylidenecyclopropylmethyl-amines

The reaction of benzyl-2-arylmethylidenecyclopropylmethyl-amine 1 with iodine in the presence of potassium carbonate or PhSeBr stereoselectively gives ring-closure product 1-iodo-2-aryl-3-azabicyclo[3.1.0]hexane or 1-phenylselenenyl-2-aryl-3-azabicyclo[3.1.0]hexane in good yields at room temperature. A plausible reaction mechanism has been proposed.     

Reaction of difluorocarbene with 2H-azirines: generation and transformations of strained azomethine ylides -- aziriniodifluoromethanides

The reaction of difluorocarbene with azirines affords a new type of azomethine ylides, viz., strained aziriniodifluoromethanides. 1,3-Dipolar cycloadditions of ylides derived from 2-unsubstituted 3-arylazirines to dimethyl acetylenedicarboxylate and aldehydes give derivatives of 2,2-difluoro-1-azabicyclo[3.1.0]hex-3-ene-3,4-dicarboxylic acids and 1,4-oxazin-3(4H)-ones, respectively. Ylides derived from 2-mono- and 2,2-disubstituted azirines undergo isomerization to 2-aza-1,3-diene derivatives. 2,2-Difluoro-1-azabicyclo[3.1.0]hex-3-enes are transformed into 2-fluoropyridine derivatives in high yields and react with amines to give 2,4-diamino-1-azabicyclo[3.1.0]hex-2-ene derivatives.     

Pd-Catalyzed Asymmetric 5-exo-trig Cyclization/Cyclopropanation/Carbonylation of 1,6-Enynes for the Construction of Chiral 3-Azabicyclo[3.1.0]hexanes

We herein disclose a mild and efficient access to chiral 3-azabicyclo[3.1.0]hexanes via a Pd-catalyzed asymmetric 5-exo-trig cyclization/cyclopropanation/carbonylation of 1,6-enynes. Various nucleophiles, such as alcohols, phenols, amines and water, are well compatible with the reaction system. This reaction forms three C−C bonds, two rings, two adjacent quaternary carbon stereocenters as well as one C−O/C−N bond with excellent regio- and enantioselectivities. The products could be further functionalized to generate a library of 3-azabicyclo[3.1.0]hexane frameworks.     

2-Azabicyclo[2.1.1]hexanes. 2. Substitutent effects on the bromine-mediated rearrangement of 2-azabicyclo[2.2.0]hex-5-enes

Methyl- and phenyl-substituted N-(ethoxycarbonyl)-2-azabicyclo[2.2.0]hex-5-enes 6 have been prepared by photoirradiation of appropriately substituted 1,2-dihydropyridines. Torquoselectivity is observed in the synthesis of the 3-endo-methyl- and 3-endo-phenyl-2-azabicyclo[2.2.0]hexenes 6c-e from 2-methyl- and 2-phenyl-1,2-dihydropyridines 5c-e. Products formed upon addition of bromine to 3-endo-, 4-, and 5-methyl- and 3-endo-phenyl-substituted N-(ethoxycarbonyl)-2-azabicyclo[2.2.0]hex-5-enes 6a-f were substituent dependent. For 6a,b, which lack substituents at C(3) or C(5), mixtures of unrearranged dibromides 8a,b and rearranged dibromides 9a,b were obtained. With the 3-endo-substituents in 6c-e, only rearranged dibromides 9c-e were formed; 5-methyl substitution afforded mainly unrearranged dibromide 8f and some allylic bromide 10. Both unrearranged 5-endo,6-exo-dibromo-2-azabicyclo[2.2.0]hexanes 8 and rearranged 5-anti-6-anti-dibromo-2-azabicyclo[2.1.1]hexanes 9 are formed stereoselectively. The dibromoazabicyclo[2.1.1]hexanes 9 have been reductively debrominated to afford the first reported 2-azabicyclo[2.1.1]hexanes 11 with alkyl or aryl substituents at C-3.     

Unexpected formation of new bicyclic γ-lactams by dimerization of α-chloroacetoacetanilides

Novel and unusual dimerization reaction of α-chloroacetoacetanilide under basic reaction condition to give structurally unique 6-oxa-3-azabicyclo[3.1.0]hexane was described.     

Reactions of 6,6-dialkyl-5,7-dioxo-4,8-dioxaspiro[2.5]octane-1,1,2,2-tetracarbonitriles with O-centered nucleophiles

The reactions of 6,6-dialkyl-5,7-dioxo-4,8-dioxaspiro[2.5]octane-1,1,2,2-tetracarbonitriles with primary aliphatic alcohols lead to the formation of alkyl 2,2,3,3-tetracyanocyclopropanecarboxylates; the reactions of the same compounds with ketone oximes give 2-amino-4,4-bis(alkylideneaminooxy)-6-(alkylidene-aminooxycarbonyl)-3-azabicyclo[3.1.0]hex-2-ene-1,5-dicarbonitriles, while with aldehyde oximes 2-amino-2-oxo-1,5-dicyano-3-azabicyclo[3.1.0]hex-2-ene-6-carboxylic acid is formed.     

Reactions of 2′-oxo-1′,2′-dihydrospiro[cyclopropane-1,3′-indole]-2,2,3,3-tetracarbonitriles with nucleophiles

2′-Oxo-1′,2′-dihydrospiro[cyclopropane-1,3′-indole]-2,2,3,3-tetracarbonitriles reacted with oxygencentered nucleophiles to form addition products at the cyano groups with conservation of the three-membered ring. Reactions of the title compounds with alcohols required the presence of base catalyst, and the products, 2-amino-4,4-dialkoxy-2′-oxo-1′,2′-dihydrospiro[3-azabicyclo[3.1.0]hex-2-ene-6,3′-indole]-1,5-dicarbonitriles, were converted into the corresponding 2-imino-2′,4-dioxospiro[3-azabicyclo[3.1.0]hexane-6,3′-indole]-1,5-dicarbonitriles and 2,2′,4-trioxospiro[3-azabicyclo[3.1.0]hexane-6,3′-indole]-1,5-dicarbonitriles by the action of acetic and sulfuric acids, respectively. The reactions with ketone oximes occurred in the absence of a catalyst, yielding 2-amino-4,4-bis(alkylideneaminooxy)-2′-oxo-1′,2′-dihydrospiro[3-azabicyclo[3.1.0]hex-2-ene-6,3′-indole]-1,5-dicarbonitriles. The reactions with thiols, aliphatic amines, and anilines were accompanied by opening of the three-membered ring. In the reactions with triphenylphosphine and thiols 2-(2-oxo-2,3-dihydro-1H-indol-3-ylidene)malononitrile was obtained, while morpholine and N,N-dimethylaniline gave rise, respectively, to 3,3-diaryl-and 3,3-dimorpholino-1H-indol-2(3H)-ones and tri- and dicyanoethylene derivatives.     

Mono- and disubstituted N,N-dialkylcyclopropylamines from dialkylformamides via ligand-exchanged titanium-alkene complexes

Dibenzylformamide was treated with cyclohexylmagnesium bromide in the presence of either titanium tetraisopropoxide or methyltitanium triisopropoxide and a variety of cyclic and acyclic alkenes and alkadienes to give new mono- and disubstituted as well as bicyclic dialkylcyclopropylamines (Tables 1-3) in yields ranging from 18 to 90 % (in most cases around 55 %). 3-Benzyl-6-(N,N-dibenzylamino)-3-azabicyclo[3.1.0]hexane (10 a) and the orthogonally bisprotected 3-tert-butoxycarbonyl-6-(N,N-dibenzyl)-3-azabicyclo[3.1.0]hexane (10 d) as well as the analogous 6-(N,N-dibenzylamino)bicyclo[3.1.0]hexane (12) were obtained as pure exo diastereomers in particularly high yields (87, 90, and 88 %, respectively) from N-benzylpyrroline (15 a), N-Boc-pyrroline (15 d; Boc=tert-butyloxycarbonyl) and cyclopentene (19). 1,3-Butadiene (52) and substituted 1,3-butadienes were also aminocyclopropanated quite well to give 2-ethenylcyclopropylamines in good yields (51-64 %). Except for alkenyl- and aryl-substituted compounds, N,N-dibenzylcyclopropylamines can be debenzylated by catalytic hydrogenation to the primary cyclopropylamines as demonstrated for 10 a and 10 d to yield the fully deprotected 10 e (93 %) and mono-Boc-protected 10 f (98 %), respectively. The latter are interesting templates for combinatorial syntheses of libraries of small molecules with a well defined distance of 4.3 A between two nitrogen atoms.     

Reactions of Substituted 2,3,7-Triazabicyclo[3.3.0]oct-2-enes and 1,2,7-Triazaspiro[4.4]non-1-enes with Halogens

Halogenation of 1-substituted 7-aryl-2,3,7-triazabicyclo[3.3.0]oct-2-ene-6,8-diones gives different products, depending on the substituent in position 1 (R¹): when R¹ = Ar, 6-chloro-3-azabicyclo[3.1.0]hexanes are formed, while compounds with R¹ = H or Me give rise to 2- or 4-chloro-2,3,7-triazabicyclo[3.3.0]oct-2-ene-6,8-diones whose thermolysis leads to formation of the corresponding 6-chloro-3-azabicyclo[3.1.0]hexanes. Chlorination of 7-aryl-1,2,7-triazaspiro[4.4]non-1-ene-6,8-diones yields 3-chloro-1,2,7-triazaspiro[4.4]non-1-ene-6,8-diones, and thermolysis of the latter affords 1-chloro-5-azaspiro[2.4]heptanes.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 1, 2005, pp. 78–88.Original Russian Text Copyright © 2005 by Molchanov, Stepakov, Kostikov.     

Tactics for the asymmetric preparation of 2-azabicyclo[3.1.0]hexane and 2-azabicyclo[4.1.0]heptane scaffolds

In this contribution, two methods are presented for the removal of benzyl-type protecting groups attached to the nitrogen atom of 2-azabicyclo[3.1.0]hexane and 2-azabicyclo[4.1.0]heptane systems. The first, based on the Polonovski reaction, is suitable for [3.1.0] systems. The second relies on an elimination process, starting from derivatives of O-methyl phenylglycinol, and is more general in terms of the substrates tolerated. Secondary bicyclic cyclopropylamines, including enantiomerically pure molecules, can thus be accessed. These compounds are then ready for further functionalisation.     

Reaction of organozinc reagents prepared from bromomalonic acid esters and zinc with 3-aryl-2-cyanopropenoic acid primary amides

Organozinc compounds prepared from bromomalonic acid esters and zinc react with 3-aryl-2-cyanopropenoic acid primary amides giving a single diastereomer of the corresponding 1-R′-4-aryl-2,6-dioxo-5-cyanopiperidine-3-carboxylic acid esters, or 3-R′-6-aryl-2,4-dioxo-5-cyano-3-azabicyclo[3.1.0]hexene-1-carboxylic acid esters.     

Hydrolysis of 6-Aryl-2-amino-4-(dicyanomethylidene)-3-azabicyclo[3.1.0]hex-2-ene-1,5-dicarbonitriles

Russian Journal of Organic Chemistry - 6-Aryl-2-(dicyanomethylidene)-4-oxo-3-azabicyclo[3.1.0]hexane-1,5-dicarbonitriles were synthesized by treatment of...     

Reaction of Substituted Methyl 2,3,7-Triazabicyclo[3.3.0]oct-3-ene-4-carboxylates and 1,2,7-Triazaspiro[4.4]non-2-ene-3-carboxylates with Iodinating Agents

Substituted methyl 2,3,7-triazabicyclo[3.3.0]oct-3-ene-4-carboxylates and 1,2,7-triazaspiro[4.4]non-2-ene-3-carboxylates react with N-iodosuccinimide (or the system iodine-silver trifluoroacetate) to give, respectively, methyl 6-iodo-3-azabicyclo[3.1.0]hexane-6-carboxylates or methyl 1-iodo-4,6-dioxo-5-azaspiro[2.4]heptane-1-carboxylates as mixtures of exo and endo isomers.     

Synthesis of novel 2-azabicyclo[2.2.0]- and [2.1.1]hexanols

Methyl- and phenyl-substituted N-(ethoxycarbonyl)-2-azabicyclo[2.2.0]hex-5-enes 6 were reacted with NBS in wet DMSO to afford bromohydrins. Mixtures of unrearranged 6-exo-bromo-5-endo-hydroxy-2-azabicyclo[2.2.0]hexanes 7a,b and rearranged 5-anti-bromo-6-anti-hydroxy-2-azabicyclo[2.1.1]hexanes 8a,b were formed stereoselectively from the parent alkene 6a and 4-methyl alkene 6b. The 5-methyl alkene 6c affords only unrearranged bromohydrin 7c and dibromohydrin 9. By contrast, solely rearranged 3-endo-substituted-2-azabicyclo[2.1.1]hexane bromohydrins 8d-f result from additions to 3-endo-methyl alkene 6d, 3-endo-4-dimethyl alkene 6e, and 3-endo-phenyl alkene 6f. As an alternative route to bromohydrins, the parent 5,6-exo-epoxide 10a and 5-endo-methyl-5,6-exo-epoxide 10b were ring opened with bromine/triphenylphosphine to afford unrearranged 5-endo-bromo-6-exo-hydroxy-2-azabicyclo[2.2.0]hexanes 11a,b, while the 3-endo-methyl epoxide 10c afforded solely the rearranged 5-anti-bromo-6-anti-hydroxy-3-exo-methyl-2-azabicyclo[2.1.1]hexane isomer 8g. Tributyltin hydride reduction of bromohydrins 7a,b and 11a afforded novel 2-azabicyclo[2.2.0]hexan-5-ols 13a,b and -6-ol 14, and bromohydrins 8a,b, 8d-g afforded new 2-azabicyclo[2.1.1]-hexan-5-ols 15a,b and 15d-g.     

Synthesis of novel azabicyclo derivatives containing a thiazole moiety and their biological activity against pine-wood nematodes

Abstract

To explore a new skeleton with nematicidal activity, a series of novel azabicyclo derivatives containing a thiazole moiety were designed, synthesized and evaluated for their nematicidal activities. The bioassay results against pine-wood nematodes (Bursaphelenchus xylophilus) showed that most of the title compounds displayed nematicidal activity at a concentration of 40?mg/L. Especially, the title compounds2-((8-methyl-8-azabicyclo[3.2.1]octan-3-yl)oxy)-4-(4-chlorophenyl)thiazole (7e), 2-((8-methyl-8-azabicyclo[3.2.1]octan-3-yl)thio)-4-phenylthiazole (10a) and 2-((8-methyl-8-azabicyclo [3.2.1]octan-3-yl)thio)-4-(4-chlorophenyl)thiazole (10e) exhibited more than 90% mortality against Bursaphelenchus xylophilus.     

Aziridines as a structural motif to conformational restriction of azasugars

In order to investigate the hypothesis that the glycosidase inhibitor isofagomine was bound to alpha- or beta-glucosidase in a 1,4B conformation, a number of bicyclic aziridines that adopt the 1,4B or B1,4 conformations were synthesised and investigated. (1R)-2-endo,3-exo-2,3-Dihydroxy-4-endo-4-hydroxymethyl-6- azabicyclo[3.1.0]hexane (5) and its N-methyl and N-benzyl analogues and (1S)-2-exo-3-endo-2,3-dihydroxy-4- endo-4-hydroxymethyl-6-azabicyclo-[3.1.0]hexane (6) were synthesised. The aziridines 5 and 6 were found to be weak or not inhibitors of alpha-glucosidase, beta-glucosidase and alpha-fucosidase.     

Reaction of Substituted 6,8-Dioxo-2,3,7-triazabicyclo[3.3.0]oct-3-ene-4-carboxylates and 6,8-Dioxo-1,2,7-triazaspiro[4.4]non-2-ene-3-carboxylates with N-Fluoropyridinium Tetrafluoroborate

Substituted 6,8-dioxo-2,3,7-triazabicyclo[3.3.0]oct-3-ene-4-carboxylates react with N-fluoropyridinium tetrafluoroborate to give mixtures of exo and endo isomers of 6-fluoro-2,4-dioxo-3-azabicyclo[3.1.0]hexane-6-carboxylates. Analogous reaction of 6,8-dioxo-1,2,7-triazaspiro[4.4]non-2-ene-3-carboxylates results in formation of syn,anti-isomeric 1-fluoro-4,6-dioxo-5-azaspiro[2.4]heptane-1-carboxylates.     

The syntheses,spectra, and some reactions of 2-phthalimidyl- and 2-phthalimidyl-4.5-dichloro-5-azabicyclo[2.1.0]pentane

Cyclobutene has been prepared by an improved method. The reaction ofN-aminophthalimide with cyclobutene or cis-3,4-dichlorocyclobutene in the presence of lead tetraacetate gives 2-phthalimidyl- (5) or 2-phthalimidyl-4,5-dichloro-5-azabicyclo[2.1.0]pentane (6), respectively. The NMR spectra of 6 showed the presence of exo (9) and endo (10) isomers. The effect of ring size on the chemical shift of the bridgehead hydrogen absorption in a series of azabicyclo[n.1.0]alkanes was examined. Several reactions of 5 and 6 and alternative syntheses of the azabicyclo[2.1.0]pentane system were investigated.