An Aza Cyclopropylcarbinyl-Homoallyl Radical Rearrangement-Radical Cyclization Cascade. Synthesis of Dibenzoimidazoazepine and Oxazepine Derivatives

作者：Khebnikov Alexander F^*; Novikov Mikhail S; Petrovskii Petr P; Stoeckli Evans Helen

来源：Journal of Organic Chemistry, 2011, 76(13): 5384-5391.

DOI：10.1021/jo200788k

The cycloaddition of the dibenzoxazepinium W-ylides, generated by heating of trans-1-aryl-7,11b-dihydro-1H-azirino[1,2-a]dibenzo[c,f]azepines, to the C=N double bond of 3-aryl-2H-azirines proceeds endo-stereoselectively giving regioisomeric cycloadducts in ca. 1:1 ration, in good overall yields. In contrast to the dibenzoxazepinium ylides, the cycloaddition of the dibenzazepinium W-ylide proceeds regioselectively but without exo-endo-stereoselectivity. The reasons for this selectivity of the cycloaddition theoretically were studied at the DFT B3LYP/6-31G(d) level. Heating adducts, (2aRS,13SR,13aRS)-13,13a-diaryl-13,13a-dihydro-1H,2aH-azireno[1',2':3,4]imidazo[1,2-d]dibenzo[b.f][1,4]oxazepines and (2aRS,13SR,13aRS)-13,13a-diphenyl-2a,7,13,13a-tetrahydro-1H-azireno[1',2':3,4]imidazo[1,2-a]dibenzo[c,f]azepine, with an excess of AIBN in toluene gave new polyheterocyclic systems via a novel aza cyclopropylcarbinyl-homoallyl radical rearrangement-radical cyclization cascade. The energy profile of the cascade was studied at the DFT UB3LYP/6-31G(d) level. The transient imidazolinylmethyl radical was trapped by the use of other radical initiators as the corresponding peroxide or alcohol.

• 出版日期2011-7-1