SECONDARY ORBITAL INTERACTIONS DETERMINING REGIOSELECTIVITY IN LEWIS ACID-CATALYZED DIELS-ALDER REACTION .2.
SECONDARY ORBITAL INTERACTIONS DETERMINING REGIOSELECTIVITY IN LEWIS ACID-CATALYZED DIELS-ALDER REACTION .2.
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DOI：
10.1021/jo00896a026
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发表时间：
1975-01-01
影响因子：
3.6
通讯作者：
OTTENBRITE, RM
中科院分区：
文献类型：
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作者：
ALSTON, PV;OTTENBRITE, RM
前线轨道理论和Lewis酸络合亲双烯分子的理论模型被用来预测路易斯酸催化不对称取代双烯与亲双烯分子之间的Diels-Alder反应的区域选择性。将这一理论方法应用于三类未分析的Diels-Alder反应，给出了预测催化对正常电子需求反应区域选择性影响的一般情况。还测定了多取代对丁二烯前线轨道系数的影响。偶极-偶极相互作用不适用于预测区域选择性的变化。用前线轨道理论预测协同环加成反应的活性和区域选择性是非常成功的。1-6提出了从前线轨道相互作用预测无催化协同[2+2Tt]和[4+2RR]环加成反应区域选择性的一般规则。此外，还确定了Lewis酸催化Diels-Alder反应的作用。亲二烯基丙烯醛与Lewis酸络合后前线轨道性质的重要变化是前线轨道能显著降低，羰基碳的LUMO系数值增大，烯烃部分的LUMO系数值差增大。根据这些变化，预测了一个完全由高二烯-LUMO亲双烯相互作用主导的催化过渡态，并大大增加了二级轨道相互作用。Houk和Strozier20还提出，对于末端系数不同的二烯来说，Lewis酸催化会增加非催化反应的区域选择性，而末端系数几乎相等的双烯则不会改变或降低区域选择性。
Frontier orbital theory and the theoretical model of the Lewis acid complexed dienophile have been used to predict the effect of Lewisacid catalysis on the regioselectivity of the Diels-Alder reaction between unsymmetrically substituted dienes and dienophiles. This theoretical approach is applied to the three general types of unca-talyzed Diels-Alder reactions and general cases for predicting the effect of catalysis on the regioselectivity of the normal electron demand reaction are given. The effectof polysubstitution on the frontierorbital coefficients of butadiene is also determined. Dipole-dipole interactions were not useful inpredicting the changes in regioselecti-vity.The use of frontier orbital theoryto predict the reactivi-ty and the regioselectivity of concerted cycloaddition reac-tions has been extremely successful. 1-6 General rules for predicting the regioselectivity ofthe uncatalyzed concerted [2+ 2tt] and [4+ 2rr] cycloaddition reactions from the frontier orbital interactions have been proposed. lc’2d’4’ob Also, the role of Lewis acid catalysis in the Diels-Alder reaction has been determined. 20’5® The important changes in the frontier orbital properties of the dienophile acrolein upon complexation with a Lewis acid was a substantial lowering of the frontier orbital energies, an increase in the magnitude of the LUMO coefficient of the carbonyl carbon, and an increase in the difference in the magnitudes of the LUMO coefficients of the alkene moiety. From these changes, a catalyzed transition state completely dominated by the HOMO diene-LUMO dienophile interaction and having greatly increased secondary orbital interactions was predicted. Houk andStrozier20 also proposed that Lewis acid catalysis will increase theregioselectivity from the un-catalyzed reaction for dienes withterminal coefficients of different magnitudes, while dienes with terminal coefficients of nearly equal magnitude will have no change or a decrease in regioselectivity.