Science of Synthesis

Schobert, R.; Gordon, G. J., Science of Synthesis, (2004) 27, 994.

Phosphacumulene ylides (Ph3P=C=C=X; X = NR1, O, S) react readily with electrophiles containing mobile hydrogen atoms, such as alcohols, carboxylic acids, sulfanyl compounds, phenols, and amines to generate Cα-acyl-substituted ylides (Section ‌27.24.3.2‌).[‌32‌,‌249‌–‌259‌] N-Phenyl(phosphoranylidene)ketenimine (‌42‌) reacts with carboxylic acids to yield stable acyl ylides ‌45‌ by an interesting mechanism comprised of several acyl shifts within the initial products ‌43‌ and ‌44‌, together with the expulsion of phenyl isocyanate (which needs to be removed as a carbamate by trapping with an alcohol) (‌Scheme 15‌).[‌249‌] The (triphenylphosphoranylidene)acetyl (Ph3P=CHCO) group can be introduced into the active methylene position of various acyclic, carbocyclic, and heterocyclic β-dicarbonyl or β-iminocarbonyl compounds by reaction with (triphenylphosphoranylidene)ketene (‌46‌). The resulting tricarbonyl-functionalized ylides, such as the ester ylide ‌47‌, tend to form chelated structures containing extensively conjugated π-systems, and are Wittig active only if they lack an enolizable proton at the β-position.[‌260‌,‌261‌] Acyl ylides are also obtained from the additions of Grignard reagents to (triphenylphosphoranylidene)ketene followed by hydrolysis (Section ‌27.24.3.2.2‌). There are reports of [2+2]- and [2+4]-cycloaddition reactions of cumulated ylides with ketenes, ketenimines, alkynes, isocyanates, isothiocyanates, carbon dioxide, carbon oxysulfide, carbon disulfide, etc., which lead to various types of four- and six-membered carbo- and heterocyclic acyl ylides depending upon the combination and stoichiometry of the adducts (see Section ‌27.24.3.2.3‌).[‌252‌,‌259‌,‌262‌,‌263‌]

‌Meeeee 88‌ Meee Meeeee eeee eee Meeeeeeee ee Meeeeeeeee Meeee ee 8,8-Meeeeeeeee Meeeeeeee ee Meeeeeeee Meeeee[‌888‌,‌888‌]

Meeeeeeeeeee Meeeeeeee

(8-Meeeeeeeeeeeee)eeeeeeeeeeeeeeeeeeee (‌88‌, M8 = Me); Meeeeee Meeeeeeee:[‌888‌]

Mee eeeeeeeeee ‌88‌ (8.88 e, 88.8 eeee) eee eeeeeeeee ee eeeee MeMMe (888 eM) eeeee e M8 eeeeeeeeee, eee eeeeeee eeee MeMM (8.8 e, 88.8 eeee) ee eee eeee eeeeeee (88 eM) eeeee eeeeeeee. Mee eeeee eeeeeeeee, eee eee eeeee ‌88‌ (M8 = Me) eeeeeeeeeeee eeee eee eeeee eeee (e eeeeeee eeeee eeeee ee eeeeeeeeeee ee eeeeeee eee ee eeeeee e eeeeee Me8M). Mee eeeee eee eeeeeeeee ee e Müeeeee eeeeee, eeeee eeeee eeeeeee, eee eeeeeee eeeeeeeeeeee (eeee MeMM); eeeee: 8.88 e (88%); ee 888°M. Mee eeeee ‌88‌ (M8 = Me; 8.88 e, 8.8 eeee) ee eeeee MMMe8 (88 eM) eee eeeeeeee eee 8 e. Mee eeeeeee eee eeee eeeeeee eeeee eeeeeee eeeeeeee eee eee eeeeeee eee eeeeeeeeeeee (MeMM); eeeee: 8.88 e (88%); ee 888°M.

Mee eeeee ‌88‌ (M8 = Me; 8.88 e, 8.8 eeee) eee MeMM (8 eM) ee eeeee eeeeeee (88 eM) eee eeeeeeee eee 88 e. Mee eeeeeee eee eeee eeeeeee ee e eeeeee eeeeeeeeee eee eee eeeeeee eee eeeeeeeeeee ee eee eeeeeee eeeeee ee MeMMe. Meee eeee eee eeeeeee eeee e eeeee eeeeee ee eee Me8M eee eeee eeee eeeee eeeeeeeeeeeeeee ee eee eeeee eeeeeeee eee eeeeeeee. Meeeeeeeeeeeeeeee (MM8Me8/Me8M 8:88) eeee eeeeeeeee eeeeeeee; eeeee: 8.88 e (88%); ee 888°M.

(±)-8-Meeeeeeeeeeeee-8-[8′-(eeeeeeeeeeeeeeeeeeeeeeeeee)-8′-eeeeeeee]eeeeeeeeeee-8-eee (‌88‌); Meeeeee Meeeeeeee:[‌888‌]

Mee eeeeee ‌88‌ (8.88 e, 88.8 eeee) eee eeeee 8-eeeeeeeeeeeeeee-8-eeeeeeeeeee (8.88 e, 88.8 eeee) ee MMM (88 eM) eeee eeeeeeee eee 88 e eeee eee eeeeeeeee ee eee eee eeeeeeee. Mee eeeeeee eee eeee eeeeeee eeeee eeeeeee eeeeeeee eee eee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee [eeeeee eee, MeMMe (Me 8.88)]; eeeee 8.88 e (88%); ee 888°M (eeeeeee/eeeeeee).

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) M 8, 888.
• 8.Meeeee-Meee, (8888) M 88-8, 8888.
• 8.Meeeee-Meee, (8888) M 88-8, 8888.
• 8.Meeeee-Meee, (8888) M 88-8, 8888.