Science of Synthesis

Schobert, R.; Gordon, G. J., Science of Synthesis, (2004) 27, 1047.

Ester ylides, formylated ylides, and dithioester ylides are readily O- or S-alkylated, respectively. The corresponding cumulated ylides can be easily prepared by α-deprotonation of the resulting vinylphosphonium salts with strong bases such as sodium amide in liquid ammonia. (Diethoxyvinylidene)triphenylphosphorane (‌148‌) may thus be obtained from the phosphonium tetrafluoroborate ‌147‌, which in turn is made by alkylating (ethoxycarbonylmethylene)triphenylphosphorane[‌300‌] with the Meerwein salt triethyloxonium tetrafluoroborate (‌Scheme 53‌).[‌186‌] A C-alkylated byproduct from this reaction must be removed by conversion into the corresponding ylide and extraction with aqueous sodium hydroxide/benzene. Likewise, the sulfur congener ‌150‌ is accessible by deprotonation of the phosphonium bromide ‌149‌, which itself is obtained by exclusive S-alkylation of (ethyldithiocarbonylmethylene)triphenylphosphorane[‌566‌] with the “softer” reagent ethyl bromide.[‌51‌] Analogously, (triphenylphosphoranylidene)acetaldehyde[‌187‌] is alkylated with ethyl bromide to give the phosphonium salt ‌151‌, deprotonation of which with sodium amide in liquid ammonia gives the ylide ‌152‌ as a highly air-sensitive crystalline solid; the formation of this compound opens access to Z-α,β-unsaturated aldehydes.[‌567‌]

‌Meeeee 88‌ Meeeeeeeeeeeeee Meeeee eeee Meeee, Meeeeeeeeee, eee Meeeee Meeeee ee Meeeeeeeee/Meeeeeeeeeeee[‌88‌,‌888‌,‌888‌]

(Meeeeeeeeeeeeeee)eeeeeeeeeeeeeeeeeeeee ‌888‌ (Meeeeee ‌88.88.8.8.8.8‌) eee ee eeeeeeee ee eeeeeeeeee (eeeeeeeeeeeeeeeeee)eeeeeeeeeeeeeeeeeeee (‌888‌) eeee eeeeee eeeeeeeee eeeeeeeee (e.e., eeeeeeeeeeee eeee, eeeeeeeeeeeeeeeeeee, eeeeeeeeeeeeeee) ee eeee (β-eeeeee)eeeee eeeeee ‌888‌, eee eeee-eeeeeeeee eeeeeeeeeee ee eeeeeee (‌Meeeee 88‌).[‌888‌]

‌Meeeee 88‌ (Meeeeeeeeeeeeeee)eeeeeeeeeeeeeeeeeeeee eeee (Meeeeeeeeeeeeeeeee)eeeeeeeeeeeeeeeeeeee[‌888‌]

Meeeeeeeeeee Meeeeeeee

(8-Meeeeeeeeeeeeeee)eeeeeeeeeeeeeeeeeeee (‌888‌) eeee (Meeeeeeeeeeeeeeeeeeeeeeeee)eeeeeeeeeeee; Meeeeee Meeeeeeee:[‌888‌]

(Meeeeeeeeeeeeeeeeeeeeeeeee)eeeeeeeeeeee[‌888‌] (88.8 e, 888 eeee) eee eeeeeee eeeeeeeee MeMe (888 eM) eeee eeeeeeee eee 8 e eeee eeeeeeee. Meeeee MeMe eee eeeeeeeee eee, eee eeeeeee eee eeeeeeeee eeee eeeeeee eeeeeee (888 eM) (MMMMMMM: eeeeeeeeee), eee eee eeeeeeeee eeeee eee eeeeeeeee ee eeeeeeeeee eeeeeee e eeeeeee eeeee eeeeee. Mee eeeee eeeeeee eee eeeeeeeeeeee eeeee (MM8Me8/Me8M) ee eeee eee eeeeeeeeeee eeeeeee ‌888‌ ee e 8:8 eeeeeee ee M/M-eeeeeee ee eee eeee ee eeeeeeeee eeeeeeee; eeeee: 88.8 e (88%); ee 888°M (eee).

M eeeeeeeeee ee MeMM8 ee eee MM8 eee eeeeeeee ee eeeeee eeeee ee Me (8.8 e; eeeeee) eee eeee eeeeeeeee eeeeeee ee MeMM8 ee eee MM8 (888 eM) eeeee eee M8. Meeee e eeeee eee eeeee ee eee eeeeeee eeeeee eeee eeee eeee ee eeee eeeeeeeeee eeee eee eeeeeeeee ee MeMM8 eee eeeeeeee. Mee eeeeeeeeeee eeeeeee ‌888‌ (88.8 e, 88.8 eeee) eee eeeee ee eeeeeee eeeeeeee eee MM8(e) eee eeeeeee ee eeeeeeeee eeeeeee e Me eeeee. Mee eeeeeee eee eeeeeee eeee eeeee Me8M (888 eM), eee eeeeeee eee eeeeee ee 88°M eee 88 eee, eee eeee, eeeee eeee eeeeeeeee ee eee eee eeeeeeee, eeeeeeee eeeeeee e Meeeeee-eeee eeeeee eeeeee. Mee eeeeee eeeeeeee eee eeeeeeeeeeee ee e eee eM, eeeee eeeeeeeee eeeee (888 eM) eee eeeee, eee eee eeeeeeeeeee eeee eeeeee eee eeeeeeeee ee eeeeeee Meeeeee eeeeee eeeeee. Mee eeeee eee eeeeeee eeeee eeeee eeeeeee eeeeeeee; eeeee: 88.8 e (88%); ee 88°M; 88M MMM (eeeeeee-e8, δ): 88.88.

Meeeee 8-Meeeee-8-(eeeeeeeeeeeeeeeeeeeeeeeeee)eeee-8,8-eeeeeeee (‌888‌, M8 = Me; M8 = MM8Me); Meeeeee Meeeeeeee:[‌888‌]

MMMMMMM: Meeeeeeeeeee eeeeeee eee ee eeeeeeee ee eeeeeee ee eee eeeeeeeee eeeeeeeee.

(Meeeeeeeeeeeeeeeee)eeeeeeeeeeeeeeeeeeee (‌888‌; 8.8 e, 88 eeee) ee eeeeeee (88 eM) eeeee ee eeeee eee eeeeeeeeee eee eeeeeee eeee eeeeee eeeeeeeeeeeee (8.8 e, 88 eeee), eeeeeeeee eee eeeee ee eee eeeeeee eeeeee eee. Meeee eeeeeeee eee 8–8 e, eee eeeeeee eee eeeeeee eeeee eeeeeee eeeeeeee eee eee eeeeeee eee eeeeeee eeee eeeee Me8M (888 eM). Meee eeeeeeeeee eeee e eeeee eee eeeeee eeeeeeee ee eee eeeee ‌888‌ (M8 = Me; M8 = MM8Me) eeeeeeeeeeee. Meeee eeee eeeeeeeee ee e Meeeeee-eeee eeeeee eeeeee eee eeeeeeeeeeeeee (eee eeeeeee); eeeee: 8.8 e (88%); ee 888–888°M; 88M MMM (MMMe8, δ): 88.8.

Mee eeeee ‌888‌ (M8 = Me; M8 = MM8Me; 88.8 e, 888 eeee) ee eeeee eeeeeee (888 eM) eee eeeeeee eeee MeMMMM (88.8 e, 888 eeee) eeeee ee eeeee eeeeeeeeee ee eee M8. Mee eeeeeee eee eeeeee ee 88–88°M eee 8–8 e eee, eeeee eeeee eeee, eee eeeeee ee e Meeeeee-eeee eeeeee eeeeee, eeeee eee eeeeee eeeee eee eeeeeee eeee e 8-ee eeeee ee eeeeeee (eeeee). Mee eeeeeeeee MeMMe eee eeeeeee ee eeeeeeeeee (eeeeee eeeee eee eeeeee eeeeee eee eeee ee eeeee 88–88°M, ee eeeee eeeeeeeee eeeeeeeeeeeeeee ee eee eeeeeee). Meeee eee eeeeeeeeee eee eeeeeeee, eee eeeeee eeee eee eeeeee eeee eee eeeeeee eee eee eeeeeeee eeeeeeeee eeee eeeeeeeeee eeeee eeeeeee eeeeeeee. Mee eeeee eeeeeee eee eeeeeeeeeeeeee eeee eeeeeee ee eeeee eeeeee-eee eeeeeeee; eeeee: 88.8 e (88%); ee 888–888°M; 88M MMM (MMMe8, δ): 8.88.

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) M 8, 888.