Question

5 The reaction below proceeds with the stereochemistry shown, with ee's between 66 and 89%. Write a reasonable mechanism for the reaction. What is the function of the SnCI? 7 00 H30 SnCL (2-5 eq) m-CPBA, CH2Cl2 (quantitative) Ph (Tetrahedron Lett. 1997, 38, 6019] Ph Ph 83-94% 6-17%

Answer 1

It is a very interesting Question, here as we know Sncl4 is a lewis acid, so it enhance the positive charge on the reaction centre, activate the attack of mCPBA. Without Sncl4  this reaction is very slow. There is two possibilities of product formation in this reaction depending on the Anti- and Syn- attack of mCPBA as seen in mechanism. Anti-attack (i) is preferable and leads the major product. While syn attack is sterically less feverable so leads to minor product.

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