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Unformatted text preview: 8-12 I nstead of borane attacking the bottom face of I-methylcycJopentene, it i s equally likely to attack the top face, leading to the enantiomer. 8-13
CH3 Et Me s=<:.
,'QH BH3 · T HF .. H H (b) V�
+ major OH mi nor-steric hindrance to attack of B H 3 OH CH3 - 8-14
Et B H3 · THF Et H (a) >=< H
Z ' ' Me �� K S S Et " OH H ) e nantiomers
R S ( b) Et Me >=< Et
E H B H3 • THF Et � ------.. --H Me' �� K � � H Et enantiomers V The enantiomeric pair produced from the Z-a l kene i s diastereomeric with the other enantiomeric pair produced from the E-al kene. Hydroboration-oxidation is stereospeci fic , that i s, eac h a l kene gives J specific s et of stereoi somers, not a random mi xture. 8- 15
(a) CO H g (O Ach H2 O ... NaBH 4 ... CO
OH (b) CO B H3 · THF .. H 202 HO - .. cp
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This note was uploaded on 02/27/2010 for the course CHEM 140 taught by Professor Wade during the Spring '10 term at Whitman.
- Spring '10