Boron enolates bearing menthone-derived chiral ligands are capable of fair to excellent diastereocontrol in their reactions with chiral aldehydes. Thioester-derived (better than ketone derived) enolates are able to control aldol stereochemistry irrespective of the aldehyde preferences. With thioacet
Apparent chelation control in aldol reactions of chiral (Me2CHO)3Ti-enolates
β Scribed by Maryellen Nerz-Stonies; Edward R. Thornton
- Publisher
- Elsevier Science
- Year
- 1986
- Tongue
- French
- Weight
- 297 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0040-4039
No coin nor oath required. For personal study only.
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Since Cram's pioneering workon chelation-control in Grignardtype of addition to chiral alkoxy carbonyl compounds/l/, a number of related reports have appeared. G ' s systematic studies concerning the relative merits of such classical reagents as RMgX, RLi and R CuLi deserve particular attention/2/.
The boron-mediated aldol reactions of the (Z)-enals 3 and 7 proceed with high levels of 1,4-stereoinduction arising from the g-substituent. Reagent control from (+)-Ipc 2 BCl can be used eectively to overturn this substrate bias, thus enabling the stereocontrolled formation of (+)-discodermolide (1)