FACE SELECTION IN ADDITIONS TO THE TRIGONAL C-2 SITE IN QUATERNIZED 5-AZAADAMANTANE DERIVATIVES

The quaternary N-allyl bromide salt 5 of allyl alpha-[2-(5-azaadamanty lidene)]benzyl ether upon warming gave the Claisen rearrangement produ cts 6 is the ratio E/Z = 93:7. The epoxidation of the N-oxide 8 of 2-m ethylene-5-azaadamantane 7 with m-CPBA gives rise to the two diastereo meric epoxides 9 in the ratio E/Z = 19:81. Reaction of the methyl iodi de salt of this olefin with bromine in water produces the E- and Z-dib romides 10 in the ratio 74:26 as well as the corresponding glycols 12 in the ratio 86:14. The same reaction in methanol gives the E- and Z-i somers of 10 alone, in the ratio of 35:65. The interpretation is that, in all of these reactions, the trigonal carbon preferably undergoes a ddition at that face which is antiperiplanar to the more electron-rich vicinal bonds, and does so by margins substantially in excess of thos e observed with the corresponding 5-fluoroadamantanes. This fact lends further strength to our previously drawn conclusion that hyperconjuga tive transition state stabilization is the principal factor in the ele ctronic component of face selection.