Catalytic Iron-Mediated [4 + 1] Cycloaddition of Diallenes with Carbon Monoxide
作者:Matthew S. Sigman、Bruce E. Eaton
DOI:10.1021/ja962908o
日期:1996.1.1
determining associative coordination of diallene to form a diallene−iron complex. The effect of coordinating solvents on this cycloaddition reaction suggests that the synthetic utility of these transformations can now be expanded to include diallenes with functional groups that may only weakly coordinate to the iron. Only one sterically demanding substituent on the diallene termini is necessary to give good
1-dibromo-2-vinylcyclopropane derivatives with MeLi yielded cyclopentadienes as the main products together with small amounts of allenic compounds (Table 1). By the same reaction 2,2,2′,2′-tetrabromobicyclopropyl derivatives yielded, in all but one case, only small amounts of diallenes; the exception is the exclusive formation of 2,7-dimethyl-2,3,5,6-octatetraene, (XIII) from2,2,2′,2′-tetrabromo-3,3,3′,
The chemical behaviour of various alkyl-substituted, acyclic conjugated bisallenes in reactions involving polar intermediates and/or transition states has been investigated on a broad scale for the first time. The reactions studied include lithiation, reaction of the thus formed organolithium salts with various electrophiles (among others, allyl bromide, DMF and acetone), oxidation to cyclopentenones
首次大规模研究了各种烷基取代的无环共轭双丙二烯在涉及极性中间体和/或过渡态的反应中的化学行为。研究的反应包括锂化、由此形成的有机锂盐与各种亲电子试剂(其中包括烯丙基溴、DMF 和丙酮)的反应、氧化成环戊烯酮和环氧化物、卤化氢(HCl、HBr 加成)、卤化(Br(2) 和 I (2)加成),以及与氯磺酰基异氰酸酯的[2+2]环加成。所得加合物通过光谱和分析方法进行了充分表征;它们构成了进一步有机转化的有趣底物。
Olefin Cycloadditions of the Electrophilic Phosphinidene Complex [iPr2N−P=Fe(CO)4]
作者:Jan B. M. Wit、Gerno T. van Eijkel、Franciscus J. J. de Kanter、Marius Schakel、Andreas W. Ehlers、Martin Lutz、Anthony L. Spek、Koop Lammertsma
Highly strained methylenephosphiranes are formed in the reaction of the new electrophilic phosphinidene complex [iPr(2)N-P=Fe(CO)(4)] with allenes. Remarkably, reaction with diallenes at 0 degrees C also leads to a phosphirane, which rearranges upon warming to room temperature to a bis-isopropylidenephospholene (see scheme).