Regioselectivity and endo/exo selectivity in the cycloadditions of the phthalazinium dicyanomethanide 1,3-dipole with unsymmetrical alkene and alkyne dipolarophiles. Unexpected reversals of regiochemistry: a combined experimental and DFT theoretical study
作者:Richard N. Butler、Anthony G. Coyne、Patrick McArdle、Desmond Cunningham、Luke A. Burke
DOI:10.1039/b101150m
日期:——
17. endo Cycloadditions were strongly favoured with alkene dipolarophiles containing π bonds in substituents on the alkene unit. With N-substituted maleimides endo products were formed exclusively even when the N-substituent was tBu or adamantyl. Only with alkoxyvinyl ethers were exo-cycloadducts encountered. The mechanisms are discussed in conjunction with DFT calculations. An X-ray crystal structure
在反应 酞菁双氰胺 1,3-偶极电子贫乏的单取代 烯烃 和 炔烃双极性亲和剂双氰胺键合到未取代的碳上,得到1-取代的吡咯并[2,1- a ]酞嗪。对于富电子的双亲亲子体,其区域化学是相反的,并且产物是2-取代的吡咯并[2,1- a ]酞嗪。发生了区域化学的意外逆转甲基丙烯酸甲酯,由于C–Me组的空间效应,主要产品是 2-外-甲基-2-内-甲氧基羰基-3,3-二氰基-1,2,3,10b-四氢吡咯并[2,1- a ]酞嗪,17。内环加成受到强烈青睐烯烃在烯烃单元上的取代基中含有π键的亲二氟体。用N-取代马来酰亚胺 即使当N-取代基为t Bu或金刚烷基时,也仅形成内生产物。只有被烷氧乙烯基醚外-cycloadducts遇到。结合DFT计算讨论了这些机制。的X射线晶体结构报道于内切- ñ -叔丁基-3,3-二氰基1,2,3,10b四氢吡咯并[2,1-一个]酞嗪-1,2-二羧酰亚胺,25。