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47.1.1.1.5.2 Method 2: Stereocontrolled Alkenations

DOI: 10.1055/sos-SD-047-00004

Schobert, R.; Hölzel, C.; Barnickel, B.Science of Synthesis, (20104761.

Most of the reported Z-selective[‌460‌‌463‌] and E-selective[‌464‌,‌465‌] Wittig alkenations of ketones that employ conventional ylides Ph3P=CHR1 are substrate-dependent and thus not generally applicable to the synthesis of tri- and tetrasubstituted alkenes with defined configuration. Of more general usability are the following variants: (1) the E-selective SCOOPY (α-substitution plus carbonyl olefination via β-oxidophosphorus ylides) reaction of aldehydes; (2) the E-selective alkenation of ketones with phosphole-derived ylides; (3) HornerEmmons alkenations with phosphonates and phosphine oxides; and (4) indirect routes based upon StorkZhao and StillGennari modifications of the Wittig or HornerEmmons protocols.

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