کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5217721 | 1383304 | 2013 | 7 صفحه PDF | دانلود رایگان |
The reactivity of a series of conformationally constrained bispropargyl sulfones with an ortho alkenyl moiety was studied. Under basic condition, these molecules underwent isomerization, first to monoallene followed by 6Ï-electrocyclization (6Ï-EC). Another cycle of isomerization and 6Ï-EC gave the bis naphthyl sulfones. No Garratt-Braverman (GB) Cyclization product could be isolated even on easing up the strain. Computations with DFT (at BP86-D3/def2-SVP level) indicated that, it is energetically more favorable for the initially formed monoallenic intermediate to undergo electrocyclization rather than isomerize to bisallene. This is in contrast to the acyclic unconstrained counterpart, where isomerization to bisallene is preferred and competing GBC/6Ï-EC of bisallenes results in mixture of products.
Journal: Tetrahedron - Volume 69, Issue 41, 14 October 2013, Pages 8724-8730