Generation and Reaction of Ammonium Ylides in Basic Two‐Phase Systems

Abstract

Reaction of the quaternary ammonium salts 2a–i with electrophilic alkenes 3, active alkylating agents 7 or aromatic aldehydes 11, carried out in basic two‐phase systems A–D, afforded cyclopropanes 4, cyanoalkenes 8 or cyanooxiranes 12 respectively, via the corresponding ammonium ylides 2+ –. The method is very simple, and gives cyclopropanes 4 and cyanoalkenes 8 in high yield. Under similar conditions, 1‐cyanodienes 8aa,ba were cyclopropanated at the γ,δ‐double bond with formation of vinylcyclopropanes 9a,b. The stereochemistry of the prepared cyclopropanes was elucidated from literature, 1H NMR spectroscopic data, NOE experiments or X‐ray single crystal analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Diastereoselective Synthesis of Spirocyclopropanes under Mild Conditions via Formal [2 + 1] Cycloadditions Using 2,3-Dioxo-4-benzylidene-pyrrolidines

“…The cyclopropanation of electron-deficient olefins and ylides, including sulfonium [ 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 ], telluronium [ 56 , 57 ], arsonium [ 58 , 59 , 60 , 61 ], and ammonium ylides [ 62 , 63 , 64 , 65 ], represents one of the most efficient and straightforward strategies to construct cyclopropane-containing frameworks. Among them, sulfonium ylides, as well-developed active units, can also react with cyclic electron-withdrawing alkenes to access synthetically challenging spirocyclopropanes [ 51 , 52 , 53 , 54 , 55 ].…”

Domino Reaction of Pyrrolidinium Ylides: Michael Addition/[1,2]-Stevens Rearrangement

“…Ammonium ylides are generated by deprotonation of quaternary ammonium salts previously synthesized − or formed in situ as quaternary derivatives of DABCO − or cinchona alkaloids. − They undergo inter- − ,, or intramolecular , Michael additions. Among Michael acceptors, there are α,β-unsaturated aldehydes, ,,, ketones, ,− ,− esters, ,− ,,, α-nitroesters, amides, ,, sulfones, ,,, lactones and lactams, acrylonitrile, − , and para -quinone methides . Usually, as a result, racemic − , or optically active ,− cyclopropanes are formed by MIRC ,, (Scheme , path A).…”

“…Among Michael acceptors, there are α,β-unsaturated aldehydes, ,,, ketones, ,− ,− esters, ,− ,,, α-nitroesters, amides, ,, sulfones, ,,, lactones and lactams, acrylonitrile, − , and para -quinone methides . Usually, as a result, racemic − , or optically active ,− cyclopropanes are formed by MIRC ,, (Scheme , path A). There are few examples of other transformations.…”

“…In continuation of our work on the development of synthetic methods utilizing rearrangements of ammonium ylides, , the reaction of N -cyanomethyl- N- methyl-2-phenylpyrrolidinium iodide ( 1a ) with acrylonitrile ( 2a ) was carried out in a 50% aqueous NaOH/CH 2 Cl 2 system. In addition to the [1,2]-rearrangement product 3a , 2-cyano-2-(2-cyanoethyl)-1-methyl-3-phenylpiperidine ( 4aa ) was formed (Scheme ).…”