α,β与β,γ不饱和键的能量偏好

Energetic preferences for alpha,beta versus beta,gamma unsaturation.

作者信息

Lee Patrick S, Du Wu, Boger Dale L, Jorgensen William L

机构信息

Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, USA.

出版信息

J Org Chem. 2004 Aug 6;69(16):5448-53. doi: 10.1021/jo049363y.

DOI:10.1021/jo049363y

PMID:15287795

Abstract

Density functional theory has been applied at the B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level to examine the energetics of alpha,beta- versus beta,gamma-unsaturation for some common organic functional groups. Specifically, the relative stabilities of allyl-X (H2C=CHCH2X) and 1-propenyl-X (H3CCH=CHX) isomers have been computed for X = methyl, vinyl, phenyl, formyl, acetyl, methoxy, methylthio, methylsulfinyl, methylsulfonyl, sulfamoyl, and methoxysulfonyl, and the results are compared to available experimental data. The intrinsic preference of 3 kcal/mol for the 1-propenyl isomer when X = CH3 is exceeded by 2-4 kcal/mol for first-row conjugating groups, but it is not met for the sulfur-containing groups. In particular, alpha,beta-unsaturation is favored by less than 1 kcal/mol for the sulfone and sulfonamide analogues, while it is preferred by 8 kcal/mol for the vinyl-substituted case. Detailed structural results and torsional energy profiles are also reported.

摘要

密度泛函理论已在B3LYP/6 - 311+G(d,p)//B3LYP/6 - 31G(d)水平上应用，以研究一些常见有机官能团的α,β - 与β,γ - 不饱和的能量学。具体而言，已计算出X为甲基、乙烯基、苯基、甲酰基、乙酰基、甲氧基、甲硫基、甲亚磺酰基、甲磺酰基、氨磺酰基和甲氧基磺酰基时烯丙基 - X（H₂C=CHCH₂X）和1 - 丙烯基 - X（H₃CCH=CHX）异构体的相对稳定性，并将结果与现有的实验数据进行比较。当X = CH₃时，1 - 丙烯基异构体具有3 kcal/mol的内在偏好，但对于第一行共轭基团，这种偏好会超过2 - 4 kcal/mol，而对于含硫基团则不满足。特别是，砜和磺酰胺类似物的α,β - 不饱和偏好小于1 kcal/mol，而对于乙烯基取代的情况，其偏好为8 kcal/mol。还报告了详细的结构结果和扭转能分布。