“…With ar oute to dienes 15 and 18 in hand and hydroxyenone 9 readily available, [9,10] as tudy of the Diels-Alder reaction was conducted on (E,anti)-19 and (Z,anti)-19,which possess the (1R)configuration (Scheme 3) identical to that at C(1) in target 4. [19] Unfortunately,n oc ycloaddition occurred upon heating (E,anti)-19 in DMSO at 150 8 8C, decomposition was observed and at higher temperatures.B ycontrast, when (Z,anti)-19 was heated to 100 8 8C, rapid intramolecular Diels-Alder was observed in 53 %y ield to give (1R,12S)-20.T he excitement over this promising result, however,w as dampened by the outcome of the esterification of 18 with ent-9, affording (Z,anti)-19 in low yield and (E,anti)-19 as side product.…”