Titanium mediated asymmetric aldol reaction with alpha-fluoropropionimide enolates

Vincent A. Brunet; David O'Hagan; Alexandra M. Z. Slawin

doi:10.1016/j.jfluchem.2007.05.012

Titanium mediated asymmetric aldol reaction with alpha-fluoropropionimide enolates

Vincent A. Brunet, David O'Hagan, Alexandra M. Z. Slawin

Research output: Contribution to journal › Article › peer-review

Abstract

Aldol reaction utilising Evans N-(alpha-fluoropropyl)-2-oxazolidinones with TiCl4 have been explored. Reactions of N-(alpha-fluoropropyl)-2-oxazolidinones with aliphatic aldehydes generated (x-fluoro-p-hydroxy-aldol products with high diastereoselectivities. When (alpha R)- and (alpha S)-N-(alpha-fluoropropyl)-2-(4S)-oxazolidinones were explored as substrates they gave rise to identical aldol diastereoisomer products. Examination of the enolates formed in each case by F-19 NMR, after treatment with TiCl4, indicated that both preparations gave the same predominant enolate. This was assumed to be the E-enolate. The alpha-fluoro-beta-hydroxy-aldol products were removed from the auxiliary either by alcoholysis or reduction and converted to the corresponding alpha,beta-difluoro products by treatment with Deoxofluor (TM) (C) 2007 Elsevier B.V. All rights reserved.

Original language	English
Pages (from-to)	1271-1279
Number of pages	9
Journal	Journal of Fluorine Chemistry
Volume	128
DOIs	https://doi.org/10.1016/j.jfluchem.2007.05.012
Publication status	Published - Oct 2007

Keywords

asymmetric synthesis
Evans auxiliary
alpha-Fluoroenolates
asymmetric aldol reactions
stereoselective fluorination
vicinal difluoro compounds
ENANTIOSELECTIVE SYNTHESIS
CONFORMATION

Access to Document

10.1016/j.jfluchem.2007.05.012

Cite this

@article{b980e9c2587a405e98216638c9efe60d,

title = "Titanium mediated asymmetric aldol reaction with alpha-fluoropropionimide enolates",

abstract = "Aldol reaction utilising Evans N-(alpha-fluoropropyl)-2-oxazolidinones with TiCl4 have been explored. Reactions of N-(alpha-fluoropropyl)-2-oxazolidinones with aliphatic aldehydes generated (x-fluoro-p-hydroxy-aldol products with high diastereoselectivities. When (alpha R)- and (alpha S)-N-(alpha-fluoropropyl)-2-(4S)-oxazolidinones were explored as substrates they gave rise to identical aldol diastereoisomer products. Examination of the enolates formed in each case by F-19 NMR, after treatment with TiCl4, indicated that both preparations gave the same predominant enolate. This was assumed to be the E-enolate. The alpha-fluoro-beta-hydroxy-aldol products were removed from the auxiliary either by alcoholysis or reduction and converted to the corresponding alpha,beta-difluoro products by treatment with Deoxofluor (TM) (C) 2007 Elsevier B.V. All rights reserved.",

keywords = "asymmetric synthesis, Evans auxiliary, alpha-Fluoroenolates, asymmetric aldol reactions, stereoselective fluorination, vicinal difluoro compounds, ENANTIOSELECTIVE SYNTHESIS, CONFORMATION",

author = "Brunet, {Vincent A.} and David O'Hagan and Slawin, {Alexandra M. Z.}",

year = "2007",

month = oct,

doi = "10.1016/j.jfluchem.2007.05.012",

language = "English",

volume = "128",

pages = "1271--1279",

journal = "Journal of Fluorine Chemistry",

issn = "0022-1139",

publisher = "Elsevier",

}

TY - JOUR

T1 - Titanium mediated asymmetric aldol reaction with alpha-fluoropropionimide enolates

AU - Brunet, Vincent A.

AU - O'Hagan, David

AU - Slawin, Alexandra M. Z.

PY - 2007/10

Y1 - 2007/10

N2 - Aldol reaction utilising Evans N-(alpha-fluoropropyl)-2-oxazolidinones with TiCl4 have been explored. Reactions of N-(alpha-fluoropropyl)-2-oxazolidinones with aliphatic aldehydes generated (x-fluoro-p-hydroxy-aldol products with high diastereoselectivities. When (alpha R)- and (alpha S)-N-(alpha-fluoropropyl)-2-(4S)-oxazolidinones were explored as substrates they gave rise to identical aldol diastereoisomer products. Examination of the enolates formed in each case by F-19 NMR, after treatment with TiCl4, indicated that both preparations gave the same predominant enolate. This was assumed to be the E-enolate. The alpha-fluoro-beta-hydroxy-aldol products were removed from the auxiliary either by alcoholysis or reduction and converted to the corresponding alpha,beta-difluoro products by treatment with Deoxofluor (TM) (C) 2007 Elsevier B.V. All rights reserved.

AB - Aldol reaction utilising Evans N-(alpha-fluoropropyl)-2-oxazolidinones with TiCl4 have been explored. Reactions of N-(alpha-fluoropropyl)-2-oxazolidinones with aliphatic aldehydes generated (x-fluoro-p-hydroxy-aldol products with high diastereoselectivities. When (alpha R)- and (alpha S)-N-(alpha-fluoropropyl)-2-(4S)-oxazolidinones were explored as substrates they gave rise to identical aldol diastereoisomer products. Examination of the enolates formed in each case by F-19 NMR, after treatment with TiCl4, indicated that both preparations gave the same predominant enolate. This was assumed to be the E-enolate. The alpha-fluoro-beta-hydroxy-aldol products were removed from the auxiliary either by alcoholysis or reduction and converted to the corresponding alpha,beta-difluoro products by treatment with Deoxofluor (TM) (C) 2007 Elsevier B.V. All rights reserved.

KW - asymmetric synthesis

KW - Evans auxiliary

KW - alpha-Fluoroenolates

KW - asymmetric aldol reactions

KW - stereoselective fluorination

KW - vicinal difluoro compounds

KW - ENANTIOSELECTIVE SYNTHESIS

KW - CONFORMATION

UR - http://www.scopus.com/inward/record.url?scp=34648814438&partnerID=8YFLogxK

U2 - 10.1016/j.jfluchem.2007.05.012

DO - 10.1016/j.jfluchem.2007.05.012

M3 - Article

SN - 0022-1139

VL - 128

SP - 1271

EP - 1279

JO - Journal of Fluorine Chemistry

JF - Journal of Fluorine Chemistry

ER -

Titanium mediated asymmetric aldol reaction with alpha-fluoropropionimide enolates

Abstract

Keywords

Access to Document

Other files and links

Fingerprint

Cite this