Cyanotrimethylammonium Methylid, Formation and Reaction with α,β-Unsaturated Carbonyl Compounds: Novel Cyclopropanation with an Ammonium Ylid

Ammonium Ylide Mediated Cyclization Reactions

“…Despite the well-known versatility of N-ylides in organic transformations[18] and recognition in 1962 that the addition of S-ylides to Michael acceptors yields the corresponding cyclopropanes,[16b] it was not until the 1980s that ammonium and pyridinium ylide mediated cyclopropanations were first described. [19, 20] The first example of the use of N(sp 3 )-based ammonium ylides for cyclopropanation reactions was reported by Bhattacharjee et al in 1982. [19] This was a remarkable and also somewhat surprising result at that time because N-ylides were considered to act more like classical carbanions and yield the corresponding Michael-type adducts rather than cyclopropanes (as observed with S-ylides).…”

“…[19, 20] The first example of the use of N(sp 3 )-based ammonium ylides for cyclopropanation reactions was reported by Bhattacharjee et al in 1982. [19] This was a remarkable and also somewhat surprising result at that time because N-ylides were considered to act more like classical carbanions and yield the corresponding Michael-type adducts rather than cyclopropanes (as observed with S-ylides). In this first example of an ammonium ylide mediated cyclopropanation, the cyanide-stabilized ammonium ylide 2 , which was generated from the simple and readily accessible ammonium salt 1 , was used to yield cyclopropanes 4 in moderate yields with low to moderate trans selectivities as illustrated in Scheme 3A.…”

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

“…Thus, cyanotrimethylammonium iodide generates an ylide upon treatment with NaH in THF, which then reacts with α,β-unsaturated carbonyl compounds to afford the corresponding cyclopropanes in 21-86 % yield. [3] Pyridinium ylides, which are produced by treating pyridinium salts with triethylamine in ethanol or DMF, react with alkenes substituted with two electron-withdrawing groups (EWGs) to give the corresponding cyclopropanes in good yields. [4] Analogous reactions with resin-bound pyridinium salts have also been investigated.…”

“…NH 3 , NaH/DMF, tBuOK/DMSO and 50 % aq. NaOH/dichloromethane with benzyltriethylammonium chloride (TEBAC) as a phase-transfer catalyst [10][11][12][13] ] revealed that ylide 2a1 + -is not prone to undergo sigmatropic rearrangements.…”

Generation and Reactions of Ammonium Ylides in Basic Two-Phase Systems: Convenient Synthesis of Cyclopropanes, Oxiranes and Alkenes Substituted with Electron-Withdrawing Groups

“…Thus, an ylide generated from cyanomethyl(trimethyl)-ammonium iodide by means of sodium hydride in THF was allowed to react with chalcones, ethyl acrylate and cinnamate, to give the corresponding cyclopropanes in 21-86% yield. 4 Pyridinium ylides formed from the corresponding salts, 5 also resinbound ones, 6 with triethylamine in ethanol 5 or DMF, 6 entered the reaction with methylidene malonate derivatives to afford functionalized cyclopropanes in good yields. However, these reactions are restricted to alkenes substituted with two electron-withdrawing groups (EWG).…”