Synthesis of chiral, non-racemic cyclopropanes

In recent years, most of the attention has focused on the stereocontrolled synthesis of cyclopropanes. The isolation of several structurally intriguing natural product has revived the interest of the scientific community for the development of new methods. Several efficient and practical chiral auxiliaries have been developed for the enantioselective cyclopropanation of olefins. The most efficient chiral auxiliaries have been specifically designed for the cyclopropanation of acyclic allylic alcohols (Table 13.3, entry 1, 2, Protocol 8),24 alkenones,25 cycloalkenones26 (Table 13.3, entry 3,4, Protocol 9), vinyl ethers27 (Table 13.3, entry 5, Protocol 10), and vinylboronate esters28 (Table 13.3, 

Stereoselective cyclopropanation of acyclic allylic alcohols glucose-derived chiral auxiliary24 1 

Caution Carry out all procedures in a well-ventilated hood, and wear disposable vinyl or latex gloves and chemical-resistant safety goggles. 

Flame dry the reaction vessel and accessories under dry argon. After cooling the apparatus to room temperature, add allylic ether 12 and CH2CI2 (120 mL). 

Cool the resulting solution to -30°C, add Et2Zn, and stir 10 min. Add diiodomethane over 1 min. 

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