Catalytic conversion of β-hydroxy carboxylic acids to olefins by tungsten(Vi) complexes: A new acyl group transfer catalyst
Catalytic conversion of β-hydroxy carboxylic acids to olefins by tungsten(Vi) complexes: A new acyl group transfer catalyst
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钨(Vi)配合物催化β-羟基羧酸转化为烯烃：一种新型酰基转移催化剂
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发表时间：
1990
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通讯作者：
J. Schwartz
中科院分区：
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作者：
Tomoya Tanzawa;J. Schwartz
在碱存在下，四氯化钨氧化钨催化{β}-羟基羧酸转化为烯烃。反应以高收率、立体特异性和高催化剂周转率进行。对{β}-羟基羧酸活化的可能化学计量步骤的检查表明，中间螯合物的形成，其结构通过{sup 1}H NMR进行了研究。用{sup 1}H和{sup 183}W核磁共振对碱的作用进行了探测，结果表明碱只是使螯合物脱质子；基地与W中心不协调。{β}-内酯是该序列的初始产物，从该序列脱羧生成烯烃产物。
Oxotungsten tetrachloride catalyzes the conversion of {beta}-hydroxy carboxylic acids to olefins, in the presence of base. The reaction proceeds in high yield, stereospecifically, and with high catalyst turnover. Examination of the likely stoichiometric steps for {beta}-hydroxy carboxylic acid activation shows the formation of intermediate chelates, structures of which were studied by {sup 1}H NMR. The role of the base was probed by using both {sup 1}H and {sup 183}W NMR, and it was shown that base simply deprotonates the chelate; base does not coordinate to the W center. {beta}-Lactones were the initial products of this sequence from which decarboxylation occurred to give the olefinic product.