228860-00-2Relevant academic research and scientific papers
Stereoselective construction of cycloheptene-fused indoline frameworks through photosensitised formal [5+2] cycloaddition
Arai, Noriyoshi,Ohkuma, Takeshi
supporting information, (2021/12/17)
Irradiation of 1-acylindole derivatives that possess a vinylcyclopropane moiety at the end of the acyl side chain by a high-pressure mercury lamp through Pyrex glass under sensitization of an aromatic ketone gave the corresponding cyclised products stereoselectively in high yields. The distribution of the products was highly dependent on the substituents on the cyclopropane ring. In the case of a simple cyclopropane, the product was a mixture of ring-expanded cycloheptene-fused indoline and all-cis-fused cyclopropylcyclobutane-fused indoline through [2 + 2] cycloaddition, while cycloheptene-fused indolines were predominantly produced via formal [5 + 2] cyclisation in the case of substituted cyclopropanes. In particular, the product selectivity was substantially high in the case of silylcyclopropane.
Direct measurements of the kinetics of 3-exo radical cyclizations using radical reporter groups
Furxhi, Eldi,Horner, John H.,Newcomb, Martin
, p. 4064 - 4068 (2007/10/03)
The E and Z isomers of the 4-(2,2-diphenylcyclopropyl)-3-butenyl radical (1), produced by laser flash photolysis of the corresponding PTOC esters in THF, cyclized to the (2,2-diphenylcyclopropyl)(cyclopropyl)methyl radical (2) that rapidly opened to 1,1-diphenyl-4-cyclopropyl-3-butenyl radicals (3). Radicals 3 were monitored by UV spectroscopy, but the observed rate constants were for the initial, relatively slow cyclizations of radicals 1 to radical 2. The Arrhenius functions determined in the temperature range of 20-58°C were log(k/s-1) = (11.46 ± 0.38) - (9.10 ± 0.54)/θ for (E)-1 and log(k/s-1) = (12.34 ± 0.32) - (10.10±0.45)/θ for (Z)-1 where θ = 2.3RT in kcal/mol and errors are at 2σ. Radical (Z)-1 cyclizes somewhat faster than radical (E)-1 as a result of a more favorable entropy of activation and despite the fact that the activation energy for cyclization of (Z)-1 through the requisite syn-transition state is greater than that for cyclization of (E)-1 through an anti-transition state.
