Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
The transformation of 36 bis(homoallylic) alcohols VII to alkenones IX and X via β-cleavage of their potassium alkoxides VIIa in HMPA has been investigated (cf. Scheme 2). These studies have established an order of β-cleavage for 2-propenyl, 1-methyl-2propenyl, 2-methyl-2-propenyl, 1,1-dimethyl-2propenyl, and benzyl groups in alkoxides 49a-56a and have allowed a comparison between the β-cleavege reaction and the oxy-Cope rearrangement in alkoxides 74a-83a. As illustrative syntheti applications, a two-step preparatio of propenyl ketones 15-42 from carboxylic esters is described, together with syntheses of ar-turmerone (48), α-damascone ((E)-71), β-damascone ((E)-109), and β-damascenone ((E)-111).
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