Chiral phosphonyl and thiophosphonyl carbanions in asymmetric alkylation and olefination reactions

A series of 3-substituted 2-benzyl-6-methyl-1,3,2-oxazaphosphorinane-2-oxides, derived from (S)-N-alkyl-4-amino-2-butanols, was prepared. The alkylation behavior of the derived lithium anions was examined as a function of the N-substituents and electrophiles. In the l-series, the methylation proceeded with high diastereoselectivity (90/10-97/3) and the benzylation selectivity ranged from 80/20 to 94/6. In the u-series, little steric influence on the methyl selectivity (83/17-85/15) was observed except in the case of sterically demanding group (R = $\rm C(C\sb2H\sb5)\sb3)$ where high diastereoselectivity (95/5) could be accomplished. An extremely high level of asymmetric induction was achieved in the alkylation of (l)-N-isopropyloxazaphosphorinane-2-oxide with a diverse array of electrophiles. Further extensions to other P-alkyl-N-isopropylphosphonamidates were also examined. Anions derived from enantiomerically enriched N-isopropyloxazaphosphorinane-2-sulfides underwent smooth electrophilic substitution with excellent diastereoselectivity in both l- and u-stereoisomers, which allowed the preparation of scalemic phosphonic acids and phosphonates with three α-substitution patterns (aryl, alkyl, and alkoxy). Synthesis of α-hydroxyphosphonates in either antipodal form could be achieved by the highly diastereoselective alkylation of anions derived from the corresponding P-methoxymethyl analog in the presence of HMPA or PMDTA.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Chen, Chien-Tien

Contributors dc:contributor

• Denmark, Scott E.

• Chemistry, Organic

Statement dc:rights

• Copyright 1994 Chen, Chien-Tien

Language dc:language

eng

Identifier

AAI9512324
(UMI)AAI9512324

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/20369