Ireland-CIaisen rearrangement

The (partial) description of the synthesis and coupling of the five fragments starts with the cyclohexyl moiety C —C. The first step involved the enantio- and diastereoselective harpless epoxidation of l,4-pentadien-3-ol described on p. 126f. The epoxide was converted in four steps to a d-vinyl d-lactone which gave a 3-cyclohexenecarboxylate via Ireland-CIaisen rearrangement (cf. p. 87). Uncatalysed hydroboration and oxidation (cf. p. 131) yielded the desired trans-2-methoxycyclohexanol which was protected as a silyl ether. The methyl car-... 

In an approach to chlorothricolide, Ireland and Varney formed the C15-C16 bond using an Ireland-CIaisen rearrangement of a macrocydic aUylic lactone (Scheme 4.91) [84]. The stereoselectivily at the a<arboxylic acid stereocenter was not an issue, since the carboxyl group was later exdsed under radical conditions. The alkene was formed soldy as the T-isomer. 

Burke et al. have employed the Ireland-CIaisen rearrangement of 6-vinyl-dioxa-nones in the synthesis of substituted pyrans (Scheme 4.92) [85]. Treatment of the... 

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