An isomerization鈥?,3-dipolar cycloaddition tandem reaction towards the synthesis of 3-aryl-4-methyl-5-O-substituted isoxazolines from O-allyl compounds

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• 作者：Stanis艂aw Krompiec^a ; ^{stanislaw.krompiec@us.edu.pl} ; Piotr Bujak^a ; Joanna Malarz^a ; Micha艂 Krompiec^a ; 艁ukasz Skó ; rka^a ; Tadeusz Pluta^a ; Witold Danikiewicz^b ; Magdalena Kania^b ; Joachim Kusz^c
• 关键词：O-Allyl systems ; Isomerization ; 1 ; 3-Dipolar cycloaddition ; Isoxazoline
• 刊名：Tetrahedron
• 出版年：2012
• 期刊代码：107_00404020
• 类别：ch
• 出版时间：29 July, 2012
• 卷：68
• 期：30
• 页码：6018-6031
• 文件大小：1956 K

摘要

A new strategy for the synthesis of 3-aryl-4-methyl-5-m>Om>-substituted isoxazolines via tandem catalytic isomerization of m>Om>-allyl systems to m>Om>-(1-propenyl) systems鈥?,3-dipolar cycloaddition (1,3-DC) to nitrile oxides is presented. The influence of the heteroatom in Ph-X-CHCHCH₃ (X=O, S, or Se) on the regio- and stereoselectivity of ArCNO 1,3-cycloaddition to these dipolarophiles is analyzed as well. The dipolarophiles were obtained via [RuClH(CO)(PPh₃)₃]-, [RuH₂(CO)(PPh₃)]- or base (KOH/18-crown-6)-catalyzed double bond migration in corresponding allyl ethers, m>Om>-allyl acetals, Phm>Sm>- and Phm>Sem>-allyl systems. Cycloadditions of nitrile oxides to m>Om>-(1-propenyl) systems were fully regioselective whereas in the reactions of ArCNO with the Phm>Sm>-(1-propenyl) and Phm>Sem>-(1-propenyl) systems both possible regioisomers were formed. It was established that within the majority of dipolarophiles of ROCHCHCH₃ type 1,3-DC is concerted, while for some dipolarophiles of RXCHCHCH₃ (X=O and R=Ph₃C, 2,3-dihydroxypropyl, tetrahydropyran-2-yl; X=S or Se and R=Ph) type 1,3-DC turns into a two-step reaction with simultaneous rotation about C-C bond. The results of the experiments have been analyzed theoretically using DFT calculations. The results of these calculations agreed well with the experimental data.