Method A TBAF in THF at rt. Method B: KFAl~ O $ l&crown-6 in MeCN at rt.* Lit. 3 mp 70-72" C. e The yield based on recovered keto ester 1st to good yields (Table 2). The rate of the cyclization reaction was not unexpectedly sensitive to bulkiness at the a-position of the R group, and the tertiary acyl substrates 15e-g required much longer reaction times than the less hindered ones, 15a-d. A low yield of 16g (52%) is largely responsible to a ...
