9-Borabicyclo 3.3.1 Jnonane

A solution of 1 mmol of butyl (-)-(S)-2-(1-phenylethylimino)acetate in THF is cooled under N2 to —78 CC. 1.1 mmol of 9-allyl-9-borabicyclo[3 3 1 Jnonane or 1.1 mmol of allylzinc bromide, respectively, is added and the resulting mixture is warmed to r.t. over a period of 12 h. A few drops of coned HC1 are added at 0°C... 

Addition of alane and borane to alkenes affords a host of alkylated alanes and boranes with various reducing properties (and sometimes bizarre names) diisobutylalane (Dibal-H ) [104], 9-borabicyclo[3.3.1]nonane (9-BBN) (prepared from borane and 1,5-cyclooctadiene) [705], mono- [106,107] and diiso-pinocampheylborane (B-di-3-pinanylborane) (both prepared from borane and optically active a-pinene) [108], isopinocampheyl-9-borabicyclo[3.3.1 Jnonane alias B-3-pinanyl-9-borabicyclo[3.3.1]nonane (3-pinanyl-9-BBN) (prepared from 9-borabicyclo [3.3.1]nonane and a-pinene) [709], NB-Enanthrane prepared from 9-borabicyclo[3.3.1]nonane and nopol benzyl ether) [770] and others. ... 

Asymmetric Reductions. NB-Enantrane is an analog of B-3-Pinanyl-9-borabicyclo[3.3.1 Jnonane (Alpine-Borane ). Since the absolute configuration of nopol is the opposite of (+)-a-pinene, the reagent provides the opposite mode of asymmetric induction. The reagent provides higher asymmetric induction than Alpine-Borane for cases where the two groups flanking the ketone are relatively small, such as methyl or ethyl alkynyl ketones (eq 2). 

Reactions with 9-borabicyclo[3.3.1 Jnonane Aldehydes from ethylene derivatives Synthesis with addition of 1-C-atom Preferential formation... 

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