A New, General Route to γ,δ-Unsaturated α,α-Dichloroketones from Allyl 2,2,2-Trichloroethyl Ethers via the [3,3]Sigmatropic Rearrangement of Intermediary 2,2-Dichlorovinyl Ethers
Process for the preparation of cyclopropylacetylene
申请人:Dupont Pharmaceuticals Company
公开号:US06288297B1
公开(公告)日:2001-09-11
The present invention relates generally to novel methods for the synthesis of cyclopropylacetylene which is an essential reagent in the asymmetric synthesis of (S)-6-chloro-4-cyclopropylethynyl-4-trifluoromethyl-1,4-dihydro-2H-3,1-benzoxazin-2-one; a useful human immunodeficiency virus (HIV) reverse transcriptase inhibitor. In the process, for example, cyclopropane carboxaldehyde is alkylated to form 1,1,1-trichloro-2-cyclopropyl-ethanol; which in turn is hydroxy protected to form 1,1,1-trichloro-2-cyclopropylethyltosylate; which in turn undergoes elimination to form cyclopropyl acetylene. This improvement provides for high conversion of inexpensive, readily available starting materials into cyclopropylacetylene, high overall yields and can be conducted on an industrial scale.
A novel chain reaction induced by cathodic reduction was found in the reaction system consisting of carbon tetrachloride, chloroform, and electrophiles such as aldehydes or vinyl acetate. The current efficiency of addition of trichloromethylanion to electrophiles was extremely high. Synthesis of an analogue of ethyl chrysanthemate using this new reaction was also described.