Addition of dimethyl phosphite to imines bearing the L‐methionine moiety and its surprisingly poor chiral assistance

Abstract

The preparation of methyl 2‐{[(dimethoxyphosphoryl)‐methyl]‐amino}‐4‐methyl‐ sulfanylbutyrates (3a–e) by the addition of dimethyl phosphite to 2‐(methylidenamino)‐4‐methylsulfanylbutyric acid methyl esters (2a–e) is described. The nearly nonexisting diastereoselectivity, which was observed in all cases, is unexpected and astonishing in light of the fact that some other amino acid esters, e.g., leucine, demonstrated very high stereoselectivity in similar reactions. The separation of formed diastereoisomers occurred. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:395–398, 2012; View this article online at http://wileyonlinelibrary.com. DOI 10.1002/hc.21029

The Kabachnik–Fields and Pudovik Reactions on the Basis of E,Z‐Citral and Its Imines and (R,S)‐Citronellal

“…On the other hand, α‐aminophosphonates have also been obtained via the interaction of acidic phosphites with imines formed as a result of the condensation of aldehydes with primary amines and amino acid esters . Chiral Schiff bases were prepared by the condensation of ( S )‐2‐hydroxy‐3‐pinanone and its ( R )‐isomer with glycine ethyl ester , aldehydes with MeO‐methionine hydrochloride , diterpenoid isosteviol , and (1 R )‐(–)‐myrtenal with aliphatic primary amines . In continuation of a study of prenyl derivative chemistry, we have involved E,Z ‐3,7‐dimethylocta‐2,6‐dienyl N ‐isobutylimines 5a obtained by the reaction of isobutylamine 3a with citral E,Z ‐1a at –20 о С in the interaction with phosphite 2 (Scheme , method B).…”