| abstract |
There are disclosed substrates of the formula: ##STR1## wherein: (a) R 1 is H or C 1 -C 4 alkyl; n (b) R 2 is H or C 1 -C 4 alkyl with the proviso that R 1 is H when R 2 is alkyl, and with the proviso that R 2 is H when R 1 is alkyl; n (c) R 3 is a leaving group including hydroxy, C 1 -C 4 alkoxy, C 2 -C 4 alkoxalkoxy, C 1 -C 7 acyloxy, and trialkylsilyloxy of less than fifteen carbons; and n (d) R 5 (1) and R 5 (2) are each H, C 1 -C 8 alkyl, or an optionally esterified or etherified hydroxy group including hydroxy, C 1 -C 4 alkoxy, C 2 -C 4 alkoxyalkoxy, C 1 -C 15 trialkylsilyloxy, C 4 -C 8 cycloalkoxy, C 1 -C 7 carboxyacyloxy, or unsubstituted heterocyclic ether of five to seven members, with the proviso that at least one of R 5 (1) and R 5 (2) is hydrogen. n A method is disclosed for the cyclization of the compounds of formula I leading to compounds of the following formulae: ##STR2## having R 4 as defined above, with R 5 being R 5 (1) or R 5 (2) as defined above, and R 7 being C 1 -C 4 alkyl. |