Science of Synthesis

Schobert, R.; Gordon, G. J., Science of Synthesis, (2004) 27, 1045.

The viability of the above route to cumulated ylides ‌141‌ (X = NR1) (‌Scheme 50‌), although straightforward and high yielding, very much depends upon the purity of the starting materials, especially that of the dichloroimines ‌140‌ (X = NR1; Hal = Cl). Complete failures are reported in cases where substrates of dubious quality are used. A more robust four-step synthesis of cumulated ylides (‌Scheme 51‌) employs isothiocyanates, which when reacted with (methylene)triphenylphosphorane give ylides ‌142‌. In turn these products can be alkylated with bromo or iodomethane forming the phosphonium salts ‌143‌. Deprotonation of the latter with sodium methoxide leads to the stabilized ylides ‌144‌, the treatment of which with sodium hexamethyldisilazanide gives ylides ‌145‌ in overall yields as good as those reported for syntheses of analogous compounds described in Section ‌27.24.3.1.1.1‌.[‌554‌]

‌Meeeee 88‌ Meeeeeeeeeeeeee Meeeee eeee (Meeeeeeee)eeeeeeeeeeeeeeeeeeee eee Meeeeeeeeeeeeee[‌888‌]

Meeeeeeeeeee Meeeeeeee

M-Meeeee(eeeeeeeeeeeeeeeeeeeeeeeeee)eeeeeeeeee (‌888‌, M8 = Me) eeee Meeeee Meeeeeeeeeeeee; Meeeeee Meeeeeeee:[‌888‌]

M eeeeeee eeeeeeee Me eeee eeee eeee ee Me8M=MM8 (88.8 e, 88.8 eeee; eee eeeeeeeeeee eee Meeeeee ‌88.88.8.8.8.8‌) ee eeeee eeeeeee (888 eM) (MMMMMMM: eeeeeeeeee) eeeeeeeee eeee eee eee eeeeeeee eee eeeeeee eeeeeeeeee ee ee eeeee eeeeee eeeeeeeeeeeeee (8.8 e, 88.8 eeee) ee eeeeeee (888 eM) eee eeeee eeeeeeee. Mee eeeeeee eee eeeeeee eee eeeeeee 88 e eee eeee eeeeeee eeee ee eeeeee ee eeeee Me8M ee eeeeeeee eee eee eeeee eeeee eeee eee eeeeee. Mee eeeeeeeeeee ee eeeeeeeee[(M-eeeeeeeeeeeeeeeeeee)eeeeeeeee]eeeeeeeeeee (‌888‌, M8 = Me) eee eeeeeeeee ee e eeeeeee eeeeee eeeeee, eeeee eeeee eeeeeee eeeeeeee, eee eeee eeeeeeeeeee ee eee eeee eeee. Me eeeeeeeeee eeeeee eee eeeeeeee ee eeeeeee eeeeee eeeeeeee ee eeeeeeeeeeeeeee (MMMe8/MeMMe); eeeee: 88.8 e (88%); ee 888°M; 88M MMM (MMMe8, δ): 88.8.

M eeeeeeee eeeeee ee eeeeeee MeMe eee eeeeeee eeeeeee e eeee ee eee eeeee ‌888‌ (M8 = Me; 88.8 e, 88.8 eeee) ee eeeee MMMe8 (888 eM) ee 8°M eeeee eee eeeeeee eeee eeeee ee eee eeeeeee eee eeeeeeeee. Meeee eeeeeeee eee e eeeeeee 8 e ee ee, Me8M (8 M) eee eeeee, eee eeeeeee eee eeeeeeee, eee eee eeeee eeeeee eeee eee eeeeeeeeeeee (MMMe8/Me8M) ee eeee eee eeeeeeeeeee eeee ‌888‌ (M8 = Me), e eeeeeee ee eee eeeeeeeee, ee e eeeeeeeee eeeeeeeeeee eeeee; eeeee: 88.8 e (88%); ee 888°M; 88M MMM (MMMe8, δ): 88.8 eee 88.8.

MeMMe (8.8 e) ee MeMM (88 eM) eee eeeeee eeeee ee e eeeeeeeeee ee eee eeeeeeeeeee eeee ‌888‌ (M8 = Me; 88.8 e, 88.8 eeee) ee eeeee MeMM (88 eM) eeee ee ee eeeee ee eeeee eee eeeeeeeeee. Mee eeeeeee eee eeeeeee eee eeeeeee 88 eee, eee eeee eee eeeeeeee eeeeeeeeee eeee eeeeeee eeeee eeeeeee eeeeeeee. Mee eeee eeeeeee eee eeeee ee ee e eeeeee eeee eeeeeee, MeMe eee eeeeeee ee eeeeeeeeee, eee eee eeeeeeee eee eeeeeee eeee Me8M eeeeeeeee eeeeeeee ee eee eeeee (‌888‌, M8 = Me) eeeeee eeeeeeeee: eeeee: 8.8 e (88%); ee 888°M; 88M MMM (MMMe8, δ): 88.88.

Mee eeeee ‌888‌ (M8 = Me; 88.8 e, 88.8 eeee) ee eeeee eeeeeee (888 eM) eeeee eee M8 eee eeeee eeeeeeee ee e eeeeeee eeee ee MeMMMM (8.8 e, 88.8 eeee) ee eeeee eeeeeee (888 eM) ee ee. Mee eeeeeee eee eeeeee ee 88°M eee 88 e eee eeee e eeeeeeeeeee ee MeMMe eee eeeeeee ee eeeeeeeeee eeeeeee e Meeeeee-eeee eeeeeee eeeeee eeeeee. Mee eeeeeeee eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee, eee eee eeeeeeeee eeeee eeeeeee eee eeeeeeeeeeee (MeMMe) ee eeeeee eeeeeee; eeeee: 8.88 e (88%); ee 888°M; 88M MMM (eeeeeeee-e8, δ): 8.88.

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) M 88-8, 8888.