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Hindered organoboron groups in organic synthesis. 14. stereoselective synthesis of alkenes by the boron-wittig reaction using aliphatic aldehydes

✍ Scribed by Andrew Pelter; Keith Smith; Said Elgendy; Martin Rowlands

Publisher: Elsevier Science
Year: 1989
Tongue: French
Weight: 210 KB
Volume: 30
Category: Article
ISSN: 0040-4039
DOI: 10.1016/s0040-4039(01)93821-3

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✦ Synopsis

In the presence of HX, carbanions MeseBCHLiRl react with afiphatic aldehydes to give alkenes.

The stereochemistry of the product alkene depends upon the nature of HX.

In our previous paper1 we showed that in the presence of TFAA or NCS, anions (1) (W&H) yield ketones rather than alkenes when reacted with aliphatic aldehydes (2).

The exception is anion (1) (W=H) (equation I), which yields methylene derivatives R*CH = CH2 (3, R1 = H), even in the presence of at least one equivalent of TFAA (Table 1).

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