Work

α-Fluorovinyl Weinreb Amides and α-Fluoroenones from a Common Fluorinated Building Block

Year: 2009

Type: article

Abstract: Synthesis and reactivity of N-methoxy-N-methyl-(1,3-benzothiazol-2-ylsulfonyl)fluoroacetamide, a building block for Julia olefination, is reported. This reagent undergoes condensation reactions with aldehydes and cyclic ketones to give alpha-fluorovinyl Weinreb amides. Olefination reactions proceed under mild, DBU-mediated conditions, or in the presence of NaH. DBU-mediated condensations proceed with either E- or Z-selectivity, depending upon reaction conditions, whereas NaH-mediated reactions are > or = 98% Z-stereoselective. Conversion of the Weinreb amide moiety in N-methoxy-N-methyl-(1,3-benzothiazol-2-ylsulfanyl)fluoroacetamide to ketones, followed by oxidation, resulted in another set of olefination reagents, namely (1,3-benzothiazol-2-ylsulfonyl)fluoromethyl phenyl and propyl ketones. In the presence of DBU, these compounds react with aldehydes tested to give alpha-fluoroenones with high Z-selectivity. The use of N-methoxy-N-methyl-(1,3-benzothiazol-2-ylsulfanyl)fluoroacetamide as a common fluorinated intermediate in the synthesis of alpha-fluorovinyl Weinreb amides and alpha-fluoroenones has been demonstrated. Application of the Weinreb amide to alpha-fluoro allyl amine synthesis is also shown.

Source: The Journal of Organic Chemistry

DOI: 10.1021/jo802784w

Authors: Arun K. Ghosh, Shaibal Banerjee, Saikat Sinha, Soon Bang Kang, Barbara Zajc

Institutions: City College of New York, City University of New York

Language: English

Topic: Fluorine in Organic Chemistry

Subfield: Pharmaceutical Science

Field: Pharmacology, Toxicology and Pharmaceutics

Domain: Life Sciences

Open Access status: green

Funder: National Center for Research Resources

Award: Cellular/Molecular Basis of Development: Research Center