โ Physical Chemistry Chemistry Question
Theoretical Problem 20
Suggest a mechanism for the following transformation (Robinson-anellation).
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Model Answer
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Rationalise the build-up of the gonane skeleton.
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Model Answer
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A prochiral ฮฑ-chloro ketone was reduced to halohydrins enzimatically (R is an alkyl group). One alcohol dehydrogenase enzyme (Rhodococcus ruber) produces the R isomer, and another (Lactobacillus brevis) gives the S isomer. Under basic conditions enantiopure epoxides were produced from the halohydrins.
Give the stereostructures of the halohydrin intermediates and those of the epoxides. Detail the mechanism of the ring closure reaction.
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Model Answer
The mechanism for the ring closure:
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The reaction does not alter the configuration around the chiral center; thus the products are:
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