Role of Anions in the Synthesis of Cyclobutane Derivatives via [2 + 2] Cycloaddition Reaction in the Solid State and Their Isomerization in Solution

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• 作者：Goutam Kumar Kole ; Geok Kheng Tan ; Jagadese J. Vittal
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：October 7, 2011
• 年：2011
• 卷：76
• 期：19
• 页码：7860-7865
• 全文大小：891K
• 年卷期：v.76,no.19(October 7, 2011)
• ISSN：1520-6904

文摘

trans-3-(4鈥?Pyridyl)acrylic acid (4-PA) is inert to photodimerization reaction both in solution and solid state. It is made photoreactive by forming salts with various acids. The anions of these salts play a key role in directing the packing of 4-PAH⁺ in the solid state. The anions CF₃CO₂^{鈥?/sup>, Cl鈥?/sup>, ClO₄鈥?/sup>, and BF₄鈥?/sup> direct the parallel alignments of 4-PAH+ in head-to-tail (HT) fashion and lead to the formation of HT-photodimer. On the other hand, bivalent anion SO₄2鈥?/sup> directs parallel alignment of 4-PAH+ in head-to-head (HH) fashion and lead to the formation of HH-photodimer. The details of the anion-controlled stereoselective syntheses of these two cyclobutane derivatives are presented. Interestingly, both cyclobutane compounds undergo isomerization from rctt-form to rctc-form in solution catalyzed by acid.}