ASYMMETRIC CATALYSIS - ASYMMETRIC CATALYTIC INTRAMOLECULAR HYDROACYLATION OF 4-PENTENALS USING CHIRAL RHODIUM DIPHOSPHINE CATALYSTS
ASYMMETRIC CATALYSIS - ASYMMETRIC CATALYTIC INTRAMOLECULAR HYDROACYLATION OF 4-PENTENALS USING CHIRAL RHODIUM DIPHOSPHINE CATALYSTS
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DOI：
10.1021/ja00084a025
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发表时间：
1994-03-09
影响因子：
15
通讯作者：
BOSNICH, B
中科院分区：
文献类型：
--
作者：
BARNHART, RW;WANG, XQ;BOSNICH, B
[Rh（手性二膦）]（+）型催化剂在25 ℃下将4-取代的4-戊烯醛转化为相应的3-取代的环戊酮，通常具有高的转换数和频率。研究了不同取代的4-戊烯醛与两种手性双膦配体的对映选择性。结果发现，与binap催化剂，几乎完全的对映体选择性观察到4-戊烯醛底物轴承4-取代的叔取代基和酯基。酮取代基给出非常高的对映选择性。分子内加氢酰化的机制进行了探讨，并建议，一个重要的考虑因素，获得高营业额的频率有关的酰基-烷基还原消除机制，推断发生类似的酯水解的过程。对映选择性的起源进行了讨论的膦和戊烯醛的取代基之间的相互作用的苯基。
Catalysts of the type [Rh(chiral diphosphine)](+) convert 4-substituted 4-pentenals into the corresponding 3-substituted cyclopentanones with generally high turnover numbers and frequencies at 25 degrees C. The enantioselectivities of various substituted 4-pentenals with two chiral diphosphines have been explored. It was found that with the binap catalyst, almost complete enantioselectivity is observed for 4-pentenal substrates bearing 4-substituted tertiary substituents and for ester groups. Ketonic substituents give very high enantioselectivities. The mechanism of intramolecular hydroacylation has been explored, and it is suggested that an important consideration for obtaining high turnover frequencies is related to the acyl-alkyl reductive elimination mechanism which is inferred to occur by a process similar to ester hydrolysis. The origin of the enantioselection is discussed in terms of the interactions between the phenyl groups of the phosphine and the substituent of the pentenal.