8 9 a, R= H; R= OEt b, R= Me; R= OEt C, R= H; R'= Me d, R= R= Me perturbed under these conditions. Hydrolyses of 4a and 5a at elevated temperature produced the acyclic substances 1 la and 12a, respectively. 12 The same products result from the hydrolysis of the silyl ether mixture, 4b and 5b, on heating. Finally, mild, aqueous acid hydrolysis of either the ketone mixture 4c and 5c or the 4d-5d mixture led to keto aldehydes llb and 12b.
