Oxymetallation. Part 18. Extensive rearrangement to a [4.2.1 ] skeleton in the bromodemercuriation of 2-bromomercurio-9-oxabicyclo[3.3.1]nonane

Abstract

The distributions of isomeric 2bromo-9-oxabicyclononanes obtained by the brominolysis of trans-2bromomercurio-9-oxabicyclo[4.2.1] nonane and of trans-2-bromomercurio-9-oxabicyclo[3.3.1 ]nonane in methanol with added sodium bromide, in dichloromethane and in pyridine, and from the bromination of 5-trimethylsilyloxycyclo-octene and of 5-t-butyloxycyclo-octene have been determined using 3C n.m.r. spectroscopy. Whereas the product distributions are generally in keeping with established mechanisms, the bromodemercuriation of the [3.3.1 ]mercurial in methanol with added sodium bromide affords the trans-[4.2.1]bromide as the major product. It is suggested that this novel skeletal rearrangement occurs via a sequence of deoxymercuriation and bromination.

Zirconocene-Mediated Route to Enantiopure 9-Oxabicyclononanes Functionalized on Both Carbon Bridges

“…The process leading to 1 is customarily favored kinetically and somewhat advantaged over that which delivers the bicyclo[3.3.1]nonane alternative 2 . Equilibration between these isomers is possible . 4-Cycloocten-1-ol, its 5-isomer,1e 9-oxabicyclo[6.1.0]nonenes, 5-alkoxycyclooct-1-enes, 1e,3c and cyclooctanol itself 6 have also proven to be suitable precursors.…”

“…Equilibration between these isomers is possible . 4-Cycloocten-1-ol, its 5-isomer,1e 9-oxabicyclo[6.1.0]nonenes, 5-alkoxycyclooct-1-enes, 1e,3c and cyclooctanol itself 6 have also proven to be suitable precursors.

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