Yahata Kenzo, Minami Masaki, Yoshikawa Yuki, Watanabe Kei, Fujioka Hiromichi
Chem Pharm Bull (Tokyo). 2013;61(12):1298-307. doi: 10.1248/cpb.c13-00666.
A methodology for selective transformations of ketones, esters, Weinreb amides, and nitriles in the presence of aldehydes has been developed. The use of a combination of PPh(3)-trimethylsilyl trifluoromethanesulfonate (TMSOTf) promotes selective transformation of aldehydes to their corresponding, temporarily protected, O,P-acetal type phosphonium salts. Because, hydrolytic work-up following ensuing reactions of other carbonyl moieties in the substrates liberates the aldehyde moiety, a sequence involving aldehyde protection, transformation of other carbonyl groups, and deprotection can be accomplished in a one-pot manner. Furthermore, the use of PEt(3) instead of PPh(3) enables ketones to be converted in situ to their corresponding O,P-ketal type phosphonium salts and, consequently, selective transformations of esters, Weinreb amides, and nitriles in the presence of ketones can be performed. This methodology is applicable to various dicarbonyl compounds, including substrates that possess heteroaromatic skeletons and hydroxyl protecting groups.
已开发出一种在醛存在下对酮、酯、Weinreb酰胺和腈进行选择性转化的方法。使用三苯基膦-三甲基甲硅烷基三氟甲磺酸酯（TMSOTf）的组合可促进醛选择性转化为其相应的、暂时保护的O,P-缩醛型鏻盐。由于在底物中其他羰基随后的反应之后进行水解后处理会释放出醛部分，因此涉及醛保护、其他羰基转化和脱保护的序列可以一锅法完成。此外，使用三乙膦（PEt(3)）代替三苯基膦（PPh(3)）可使酮原位转化为其相应的O,P-缩酮型鏻盐，因此可以在酮存在下对酯、Weinreb酰胺和腈进行选择性转化。该方法适用于各种二羰基化合物，包括具有杂芳族骨架和羟基保护基的底物。
