3-(4-Methoxyphenyl)-5,5,5-triphenyl-4,5-dihydro-1,2,5.lambda.~5~-oxazaphosphole 71426-74-9 AIDS-128889 AIDS128889 Methyl 4-(5,5,5-triphenyl-4,5-dihydro-1,2,5.lambda.~5~-oxazaphosphol-3-yl)phenyl ether NSC304610