The hydroboration of 1,4,8-nonatriene (1), 5-methyl-1,4,8-nonatriene (2), 1,3,7-octatriene (3), and trans,trons,irans-1,5,9-cyclododecatriene (4) with borane in tetrahydrofuran (THF) and triethylamine-borane Was studied. The hydroboration of the acyclic trienes with borane in THF at 0 °C produced monomeric bicyclic boranes in low yields. Moreover, thermodynamically stable organoboranes with fused six-membered rings, such as 9-boradecalin (15) and 10-methyl-9-boradecalin (20), were not formed as the major monomeric cyclic products.However, thermal treatment of the hydroboration product from 1 produced 15 as the only monomeric bicyclic organoborane in high yield. The thermodynamically favored major product from 2 was 20 which amounted to 62% of the monomeric boranes formed in 74% yield. With 1 and 2, both borane in THF and triethylamine-borane gave comparable results after thermal treatment. However, in the hydroboration of 3, use of triethylamine-borane resulted in a considerably higher yield of perhydro-8-boraindan. The carbonylation-oxidation of 15 provided an 80:20 mixture of cis-and trons-9-decalols. The ratio of cis-10-methyl-9-decalol to its trans isomer obtained by the carbonylation-oxidation of 20 was at least 62:1. The carbonylation-oxidation of 3 produced only cis-8hydrindanol. The hydroboration of the cyclic triene 4 followed by thermal treatment at 160 °C for 6 h produced a mixture consisting largely of cts,trarw-perhydro-9b-boraphenalene (6) and a constitutional isomer in 83% yield. However, thermal treatment at 200 °C for 6 h provided a 92:8 mixture of 6 and its all-cis isomer 5, uncontaminated with the constitutional isomer. The hydroisomerization of 5 or 6 at 220 °C in the presence of triethylamine under 140 atm of hydrogen gave an equilibrium mixture of 88 ± 1 % 5 and 12 ± 1% 6. The difference between the free energies of 5 and 6 was estimated to be 1.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.