Journal of Organic Chemistry 2010-02-19

A facile and efficient synthesis of 3,3-dimethyl isopropylidene proline from (+)-3-carene.

Latha G Nair, Anil Saksena, Raymond Lovey, Mousumi Sannigrahi, Jesse Wong, Jianshe Kong, Xiaoyong Fu, Viyyoor Girijavallabhan

Index: J. Org. Chem. 75(4) , 1285-8, (2010)

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Abstract

A highly efficient and practical route to 3,4-isopropylidene proline I, starting from (+)-3-carene, was developed. The three continuous stereocenters were constructed using the inherent chirality of the starting natural product 2. The overall yield for the 12-step synthesis is 34%. The optimized sequence leading to 1 has been successfully applied on a multigram scale, thereby establishing the practicality of this route.