Asymmetric Diels-Alder reaction with %26gt; C=P-functionality of the 2-phosphaindolizine-eta(1)-P-aluminium(O-menthoxy) dichloride complex: experimental and theoretical results

作者：Jangid Rajendra K; Sogani Nidhi; Gupta Neelima; Bansal Raj K^*; von Hopffgarten Moritz; Frenking Gernot

来源：Beilstein Journal of Organic Chemistry, 2013, 9: 392-400.

DOI：10.3762/bjoc.9.40

• aluminium(O-menthoxy) dichloride
• asymmetric synthesis
• %26gt
• C=P-functionality
• DFT calculations Diels-Alder reaction

The Diels-Alder reaction of the 2-phosphaindolizine-eta(1)-P-aluminium(O-menthoxy) dichloride complex with dimethylbutadiene was investigated experimentally and computationally. The %26gt;C=P-functionality of the complex reacts with 2,3-dimethylbutadiene with complete diastereoselectivity to afford [2 + 4] cycloadducts. Calculation of the model substrate, 3-methoxycarbonyl-1-methyl-2-phosphaindolizine-P-aluminium(O-menthoxy) dichloride (7a), at the DFT (B3LYP/6-31+G*) level reveals that the O-menthoxy moiety blocks the Re face of the %26gt;C=P-functionality, due to which the activation barrier of the Diels-Alder reaction of 7a with 1,3-butadiene, involving its attack from the Si face, is lower. It is found that in this case, the exo approach of the diene is slightly preferred over the endo approach.

• 出版日期2013-2-18