Patent ID: 7754902

Claim:
A method of stereoselective cyclopropanation of vinyl dihydrobenzofuran (VBF) that comprises combining a carbene precursor with a chiral catalyst of the formula (V) or (VI): wherein: is VBF; R 1 and R 2 are each independently selected from the group consisting of hydrogen, substituted or unsubstituted C 1-8 alkyl, substituted or unsubstituted C 3-8 cycloalkyl, substituted or unsubstituted C 3-10 heterocyclyl, substituted or unsubstituted C 6-10 aryl, substituted or unsubstituted C 5-10 heteroaryl, and substituted or unsubstituted arylalkyl; R 3 and R 4 are each independently selected from the group consisting of substituted or unsubstituted C 1-8 alkyl, substituted or unsubstituted C 3-8 cycloalkyl, C 1-10 alkoxy, C 1-12 alkylamino, substituted or unsubstituted C 3-10 heterocyclyl, substituted or unsubstituted C 6-10 aryl, substituted or unsubstituted C 5-10 heteroaryl, and substituted or unsubstituted arylalkyl, where R 3 and R 4 together with the atoms to which they are attached may form a ring; and the chiral catalyst is formed in situ.