55551-77-4Relevant academic research and scientific papers
Cyclization of aryllithiums tethered to methylenecycloalkanes: Stereoselective synthesis of 4α-substituted cis-hexahydrofluorenes
Bailey, William F.,Daskapan, Tahir,Rampalli, Sriram
, p. 1334 - 1338 (2007/10/03)
The cyclization of an aryllithium tethered to a methylenecycloalkane, generated from 2-(o-bromobenzyl)-1-methylenecycloalkanes 1, 2, and 3 by low-temperature lithium-bromine exchange, has been found to be a kinetically slow but thermodynamically favorable process that proceeds at a convenient rate in an exclusively 5-exo fashion when solutions of the aryllithium in n-heptane-di-n-butyl ether (9:1 v/v) are warmed to 45 °C. The cyclization affords stereoisomerically pure cisfused products (7 and 8) when the methylenecycloalkane is five- or six-membered but it is less stereoselective when the methylenecycloalkane is seven-membered. The ring-closure of the aryllithium derived from 2-(o-bromobenzyl)-1-methylenecyclohexane (2) provides an experimentally convenient route to stereoisomerically pure 4a-substituted cis-hexahydrofluorenes in 60-90% isolated yield.
Regioselective Aryl Radical Cyclization. 1. Stereocontrolled Synthesis of Linearly Condensed Hydroaromatic Carbocyclic Systems through 6-endo-ring Closures
Pal, Sitaram,Mukhopadhyaya, Jayanta K.,Ghatak, Usha Ranjan
, p. 2687 - 2694 (2007/10/02)
The stereocontrolled synthesis of trans-octahydroanthracenes 3, 11a-c, and 14a-c and trans-octahydro-5aH-cycloheptanaphthalene (27) through implementation of an efficient and highly regioselective 6-endo-trig-aryl radical cyclization of the respective 2-(o-bromoaryl)-1-methylenecyclohexanes 2, 10a-c, and 13a-c and 2-(o-bromobenzyl)-1-methylenecycloheptane (41) with tri-n-butyltin hydride id described.The radical cyclization of 2-(o-bromobenzyl)-1-methylenecyclopentane (43), in contrast, produced a mixture of the cis- and trans-hexahydro-1H-benzindenes (38) and (37).
