CHAPTER 9: Question 6

 

Simple Answers

Compound A is a derivative of cis-decalin, and the product will also be a derivative of cis-decalin. Cis-decalin is a conformationally flexible molecule in which the six membered rings can undergo chair-chair interconversion. This allows the product to adopt a conformation with both bromine atoms in equatorial positions.

 Compound B however, is a derivative of trans-decalin, and the product will also be a derivative of trans-decalin. Trans-decalin is conformationally rigid with both six membered rings being locked into a single chair conformation. The addition of bromine to the alkene of B initially produces the diaxial dibromide, so the bromine
atoms have to stay in axial positions.

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