P[N(i-Bu)CH2CH2]3N: Nonionic Lewis Base for Promoting the Room-Temperature Synthesis of α,β-Unsaturated Esters, Fluorides, Ketones, and Nitriles Using Wadsworth-Emmons Phosphonates

The bicyclic triaminophosphine P(RNCH2CH2)(3)N (R = i-Bu, 1c) serves as an effective promoter for the room-temperature stereoselective synthesis of alpha,beta-unsaturated esters, fluorides, and nitriles from a wide array of aromatic, aliphatic, heterocyclic, and cyclic aldehydes and ketones, using a range of Wadsworth-Emmons (WE) phosphonates. Among the analogues of 1c [R = Me (1a), i-Pr (1b), Bn (1d)], 1a and 1b performed well, although longer reaction times were involved, and Id led to poorer yields than 1c. Functionalities such as cyano, chloro, bromo, methoxy, amino, ester, and nitro were well tolerated. We were able to isolate and characterize (by X-ray means; see above) the reactive WE intermediate species formed from 2b and 1c.