2 июля, 2015 
Malyar 2-Methylhept-2-en-6-one, usually referred to simply as methylhep — tenone, is a useful synthon for the total synthesis of terpenes. One early synthesis of this intermediate employed the Carroll reaction, the substrate for which is prepared by the addition of acetylene to acetone and subsequent partial hydrogenation to 2-methylbut-3-en-2-ol, as shown in Scheme 4.5. Addition of acetylene to methylheptenone gives dehydrolinalool, which can be hydrogenated to linalool using a Lindlar catalyst.
Ill
Scheme 4.5
The Carroll reaction occurs when a /і-ketoester is treated with an allylic alcohol in the presence of base, or when an allyl ester of a /?- ketoacid is heated. Scheme 4.6 shows the mechanism of the latter.
The disadvantage of this process is that it is not very atom efficient. The elimination of carbon dioxide means that bulk is carried through the process only to be lost towards the end, which is undesirable from both the cost and environmental impact standpoints.
Scheme 4.6
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