FACILE SYNTHESIS OF ALPHA,BETA-UNSATURATED NIOBIUM ACYLS VIA GAMMA-HYDRIDE ABSTRACTION

被引:9
作者
HNEIHEN, AS [1 ]
FERMIN, MC [1 ]
MAAS, JJ [1 ]
BRUNO, JW [1 ]
机构
[1] WESLEYAN UNIV,HALL ATWATER LABS,MIDDLETOWN,CT 06459
基金
美国国家科学基金会;
关键词
D O I
10.1016/0022-328X(92)83191-J
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
The niobocene ketene complexes [C5H4(SiMe3)]2Nb(Cl)(eta-2-C,O-O=C=C(R)CH2R') (1) undergo a facile reaction with Ph3C+BF4- to give the cationic alpha,beta-unsaturated metal acyls of general formula [[C5H4(SiMe3)]2Nb(Cl)(eta-2-C(O)CR=CHR')][BF4]. The reaction is stereospecific for the production of E-alkenes, but these undergo slow isomerization to a mixture of E and Z isomers. If both ketene substituents contain accessible allylic hydrogens, the reaction shows little regioselectivity. Preliminary mechanistic studies are consistent with a direct hydride abstraction rather than an electron-transfer/H atom transfer sequence.
引用
收藏
页码:C33 / C37
页数:5
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