ChemInform Abstract: THE FORMATION OF CONDENSED AZIRIDINES BY REDUCTION OF 2‐CYANOHEXAHYDROINDOLIUM SALTS WITH LITHIUM TETRAHYDROALUMINATE

Abstract

Die durch Cycloaddition aus den Enaminen (I) mit α‐Chloracrylnitril (II) leicht zugänglichen Hexahydroindoliumsalze (III) lassen sich mit LiAlH4 zu den tricyclischen Aziridinen (IV) reduktiv cyclisieren.

A Three-Component Reaction for the Synthesis of 1-Azabicyclo[3.1.0]hexane-3-enes

“…Previously, many methods have been developed for the synthesis of nitrogen-bridged heterocycles. 7 The most common synthetic routes reported for the preparation of nitrogen-bridged heterocycles include (i) Diels−Alder reaction between 2H-azirine and Danishefsky's diene yielding 1azabicyclo[4.1.0]hept-3-ene, 8 (ii) [4 + 2] cycloaddition (aza-Diels−Alder reaction) of imine-substituted dihydropyridines in the presence of CuCl 2 and NEt 3 , 9 (iii) photocycloaddition reaction of 2,5-diazidohexa-2,4-diene and 2,3-dimethylbuta-1,3diene to give the corresponding azabicyclo[4.1.0]hept-3-ene, 10 (iv) the reaction of cyclopentadiene and 2H-azirine esters leading to an azatricyclo products, 11 (v) reduction of 2cyanohexahydroindolium salts with LiAIH 4 and hydrolysis with NaOH, 12 and (vi) cationic cyclization of an N-allyl group onto the α-oxocarbenium ion 13 and nucleophilic attack of PhLi on perfluoro-2,6-dimethyl-1-azacyclohexene to give the corresponding azabicyclo[3.1.0]hexane. 14 As part of our current studies on the development of efficient and straightforward methods to prepare organic compounds from readily available building blocks, 15 herein we report a simple and efficient method for the synthesis of 1azabicyclo[3.1.0]hexenes via a unprecedented three-component reaction between aryl aldehydes, malononitrile, and hydroxylamine hydrochloride in water to afford the title compounds 3a−h in good to excellent yields (Scheme 1 and Table 1).…”

“…Previously, many methods have been developed for the synthesis of nitrogen-bridged heterocycles . The most common synthetic routes reported for the preparation of nitrogen-bridged heterocycles include (i) Diels–Alder reaction between 2 H -azirine and Danishefsky’s diene yielding 1-azabicyclo[4.1.0]­hept-3-ene, (ii) [4 + 2] cycloaddition (aza-Diels–Alder reaction) of imine-substituted dihydropyridines in the presence of CuCl 2 and NEt 3 , (iii) photocycloaddition reaction of 2,5-diazidohexa-2,4-diene and 2,3-dimethylbuta-1,3-diene to give the corresponding azabicyclo[4.1.0]­hept-3-ene, (iv) the reaction of cyclopentadiene and 2 H -azirine esters leading to an azatricyclo products, (v) reduction of 2-cyanohexahydroindolium salts with LiAIH 4 and hydrolysis with NaOH, and (vi) cationic cyclization of an N -allyl group onto the α-oxocarbenium ion and nucleophilic attack of PhLi on perfluoro-2,6-dimethyl-1-azacyclohexene to give the corresponding azabicyclo[3.1.0]­hexane…”