Theoretical studies of nucleophilic additions of organocopper reagents to acrolein. Rationalization of the differences in regioselectivity in the reactions of methylcopper and methyllithium
Theoretical studies of nucleophilic additions of organocopper reagents to acrolein. Rationalization of the differences in regioselectivity in the reactions of methylcopper and methyllithium
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DOI：
10.1021/ja00195a017
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发表时间：
1989-06
影响因子：
15
通讯作者：
A. Dorigo;K. Morokuma
中科院分区：
文献类型：
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作者：
A. Dorigo;K. Morokuma
已经对丙烯醛中添加甲基锂和甲基铜进行了从头算分子轨道研究。已经定位了加成到羰基（得到最终产物醇）、碳-碳双键以及整个系统（两者都会导致饱和酮的形成）的过渡态。 HF/3-21G（具有全面几何优化）、HF/6-31G* 和 MP2/6-31G* 水平的计算表明，甲基锂与羰基的反应优先于双键的共轭加成，与实验数据一致。在所有含铜物质的计算中，使用有效核心电势代替内壳层电子，而价态（3d、4s和4p）轨道则由单f和双f质量的基组表示。在 HF/3-21G-ECP (SZ) 和 -ECP (DZ) 水平上进行计算，并进行全面的几何优化，并在 HF/6-31G*-ECP (DZ) 水平上进行单点能量计算，在选定的情况下，在 MP2/6-31G*-ECP (DZ) 和 MP4/6-31G*-ECP (DZ) 水平上进行单点能量计算。所有计算表明，通过六元过渡态在 x 系统中进行 1, 4 加法比 1, 2 加法更有优势。据计算，通过四元过渡态的 1, 4-加成稍微不利于羰基的 1, 2-加成。讨论了在溶液中观察到的 1, 4-加成偏好的可能原因。
Ab initio molecular orbital studies of the addition of methyllithium and methylcopper to acrolein have been performed. Transition states for addition to the carbonyl group (which gives the alcohol as the final product), to thecarbon-carbon double bond, and across the system (both of whichlead to formation of the saturated ketone) have been located. Calculations at the HF/3-21G (with full geometry optimization), HF/6-31G*, and MP2/6-31G* levels indicate that reaction of methyllithium with the carbonyl group is preferred to conjugate addition to the double bond, in agreement with experimentaldata. In the computations of all species containing copper, an effective core potential was used in place of the inner-shell electrons, while the valence (3d, 4s, and4p) orbitals were represented by basissets of single-and double-f quality. Calculations at the HF/3-21G-ECP (SZ) and-ECP (DZ) levels were performed withfull geometry optimization, and single-point energy calculations were carried out at the HF/6-31G*-ECP (DZ) and, in selected cases, MP2/6-31G*-ECP (DZ) and MP4/6-31G*-ECP (DZ) levels. All calculations indicate that 1, 4-addition across the x system via a six-membered transition state is greatly favored over 1, 2-addition. 1, 4-Addition via a four-membered transition state is calculated to be slightly disfavored with respect to 1, 2-addition to the carbonyl group. Possible reasons for theobserved preference for 1, 4-addition in solution are discussed.