(a) Geranyl pyrophosphate is methylated by S-adenosylmethionine (SAM; Sec. 11.7B) in the reaction shown in Fig. P17.41, which is catalyzed by the enzyme geranyl pyrophosphate C-methyl transferase. Assuming that the enzyme provides acidic and basic groups as needed, provide a curved-arrow mechanism for this transformation.

(b) The product of the reaction in (a) is converted into 2-methylisoborneol in an electrophilic addition reaction catalyzed by the enzyme 2-methylisoborneol synthase. Assuming the presence of acids, bases, and water as needed, suggest a curved-arrow mechanism for the reaction. (Before starting, relate the carbons of the product to those of the starting material and thus establish the connections that must be made. Then provide a plausible mechanism for those connections that involves carbocation intermediates.)

Transcribed Image Text:

OH 2-methylisoborneol