206987-08-8Relevant academic research and scientific papers
Thermal and lewis acid catalyzed intramolecular ene reactions of allenylsilanes
Weinreb, Steven M.,Smith, Daniel T.,Jin, Jian
, p. 509 - 521 (1998)
Intramolecular ene reactions of allenylsilanes can be effected with a variety of imines, aldehydes and alkenes as enophiles, forming five and six membered rings. These reactions are cis stereoselective in all cases studied, and appear to proceed via a concerted, pericyclic process. The cycloadditions all generally occur under mild thermal conditions and some involving imino enophiles can also be effected at lower temperatures using Lewis acid catalysis.
Inter- and intramolecular [4+2] cycloaddition of nitroalkenes with allenylsilanes. A case of unexpected regioselectivity
Denmark, Scott E.,Gomez, Laurent
, p. 129 - 136 (2007/10/03)
A conjugated nitroalkene tethered to an allenylsilane undergoes formal [4+2] cycloaddition in the presence of tin tetrachloride to afford a bicyclic nitronate. The stereo- and regiochemical course of the reaction was established by a subsequent dipolar cycloaddition with 4-bromophenyl acrylate to generate a crystalline nitroso acetal. Single crystal X-Ray crystallographic analysis of the nitroso acetal revealed an unexpected stereostructure which arose from attack of the nitroalkene on the central carbon of the allenylsilane and closure of the oxygen atom on the terminal carbon. This outcome is interpreted as arising from a stepwise reaction via a silicon-stabilized carbocation which can undergo rotation to an allylic cation prior to ring closure. An intermolecular example of this same process was also documented.
