832142-18-4Relevant articles and documents
Cyclopropyl building blocks for organic synthesis, part 100.[?] Advanced syntheses of cyclopropylideneacetates - Versatile multifunctional building blocks for organic synthesis
Limbach, Michael,Dalai, Suryakanta,De Meijere, Armin
, p. 760 - 766 (2007/10/03)
A well reproducible and inexpensive preparation of the cyclopropylideneacetates 2-4 has been developed. The key intermediate 2-(1′-mesyloxycyclopropyl)acetic acid (8), produced either from methyl phenylacetate (1) or 3,3-dimethoxypropionate (5-Me) and 3,3-diethoxypropionate (5-Et) in a sequence of Kulinkovich reductive cyclopropanation, mesylation and oxidative cleavage or cleavage and oxidation, respectively, was either converted to the benzyl ester 11b, or chlorinated (brominated) via the in situ formed acid chloride. The α-chloro- 12a and α-bromo ester 12b were dehydromesylated by treatment with triethylamine to furnish methyl 2-chloro-2-cyclopropylideneacetate (3-Me) and the 2-bromo analogue 4-Me with an overall yield of 68% (65%, 68%) and 52% (49%, 51%) respectively, starting from 1 (5-Me, 5-Et). The parent benzyl cyclopropylideneacetate 2-Bn was obtained by dehydromesylation of 11b with potassium t-butoxide in t-butyl methyl ether with an overall yield of 60% (57%, 9%) from 1 (5-Me, 5-Et).
