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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 16, Number 1
BKCSDE 16(1)
January 20, 1995 

Comparison of Stereoselectivity in the Reactions of Crotylmetal Reagents with Dicobalt Hexacarbonyl-Complexed and Uncomplexed Propynals
Sang-Kyu Park*, Seok-In Kim, In-Ho Cho
The diastereoselectivity of addition reaction of crotylmetal reagents to cobalt-complexed acetylenic aldehydes and metal-free aldehydes was examined. The anti-diastereomer was the predominant product when the crotyl metallics were Cr, Sn, and Zr. In THF, the uncomplexed aldehydes normally gave higher anti-diastereoselectivity. However, the cobalt-complex of silicon-substituted propynals with three bulky substituents produced increased proportions of syn-diastereomer. In DMF, the selectivity shifted towards syn-isomer except in the case of dimethylphenylsilyl substituent. When tributylstannane was used in the presence of BF3 etherate, moderate syn- selectivity was observed with uncomplexed aldehydes, but only decomposed products from complexed aldehydes.
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