Science of Synthesis

Schobert, R.; Hölzel, C.; Barnickel, B., Science of Synthesis, (2010) 47, 61.

The SCOOPY (α-substitution plus carbonyl olefination via β-oxidophosphorus ylides) variant of the Wittig alkenation allows for the concomitant substitution of the ylidic carbon atom with residues other than hydrogen (e.g., alkyl, hydroxymethyl) to give trisubstituted alkenes with defined configuration.[‌14‌,‌15‌,‌466‌–‌469‌] In this procedure an unstabilized triphenylphosphonium ylide is prepared from its salt and a lithium base (PhLi or BuLi) and then treated with an aldehyde. The resulting mixtures of the intermediate erythro- and threo-betaines are then deprotonated by adding a second equivalent of the same lithium base at −30°C to give predominantly the lithiated threo-isomer of betaine ‌129‌. This can be intercepted by electrophiles other than a proton, giving rise to trisubstituted alkenes ‌130‌ with the electrophile located at the original ylidic α-carbon atom and normally positioned cis to the former aldehyde substituent R2 (‌Scheme 44‌). SCOOPY reactions have been reported with iodomethane[‌15‌] and, probably most importantly, with formaldehyde to yield trisubstituted E-allylic alcohols.[‌467‌,‌468‌] This hydroxymethylation usually results in a selective loss of the oxyanion from the original carbonyl component regardless of the sequence of addition of the two aldehydes used in this process.[‌469‌] High stereoselectivities are achieved if formaldehyde is added last. When aldehydes other than formaldehyde are used, invariably the oxyanion from the second aldehyde is eliminated as a phosphine oxide.

‌Meeeee 88‌ Meeeeeeeeeeeee Meeeeee ee eee MMMMMM Meeeee[‌88‌,‌88‌,‌888‌–‌888‌]

‌Meeeeeeeeee 88‌

M8	M8	M+	M	Meeee (M/M)	Meeee (%) ee ‌888‌	Mee
Me	Me	MeM	Me	8:88	88	[‌88‌]
Me	(MM8)8Me	MMMM	MM8MM	88:8	88	[‌888‌]
Me	Me	MMMM	MM8MM	88:8	88e	[‌888‌]
Me		MMMM	MM8MM	–e	–e	[‌888‌]

e Mee eeeeeeeeeeeee 8-eeeeee-8-eeeeeeeeee-8-ee-8-ee (88%) eee eeee eeeeeeee.

e Mee eeeeeee eeeee eee eeeeeeee ee ee “M eeeeeeeeeeeeee” eee “eeeeeeeee” eeeeeee eeeeeee eeeeeeeeeeeee.

Meeeeeeeeeee Meeeeeeee

(M)-8-Meeeeee-8-eeeeeeeee-8-eee [‌888‌, M8 = Me; M8 = (MM8)8Me; M = MM8MM]; Meeeeee Meeeeeeee:[‌888‌]

MMMMMMM: Meeeeeeeeeee ee e eeeeeeee eeeee eeeeeeeeee, e eeeeee eee, eeee, eee eeeeeeeeeee eeeee eeeeeeee, eee e eeee eeeeeeeeee.

Meeeeeeeeeeeeeeeeeeeeeeeeeeeee (88.8 e, 88 eeee), eeeeeee eeeeeeee eeee eeeeeeeeeeeeeeeeeeeeeeeee eeeeeee eee MeMe ee e eeeeeee ee MMM (888 eM) eee eeeeee (88 eM), eee eeeeee ee −88°M eee eeeeeee ee eeee eeee eeeeeee (88 eeee), eeeeeeeee eee eee eeeee ee eee eeeeeee eeeeeeee eeeeeeeeeeeeeee. MeMe (88 eeee, 8 eeeee) eee eeeee ee eeee eeeeeeeeeee, eee eee eeeeeee eee eeee eeeeeee ee eeee ee 8°M eee eeeeeee eee 88 eee. Meeeeeeee MMMM (88 eeee) [eeeeeeee ee eeeeeeeeee e eeeeeee ee eeeeeeeeeeeeeeee (8 e), MMM (888 eM), eee e eee eeeee ee MM8•MMe8 eeee e Meeeeee eeee eeee ee −88°M] eee eeeee ee e 8.8 M eeee ee MMM (88 eM), eee eee eeeeeeeee eeeeeeeee eeeeeeeeee eee eeeeeee eee 88 e ee ee. M8M (88 eM) eee eeeee ee eee eeeeeee, eee eeeeeeee eee eeeeeeeee eee eeeeeee 8 e. Mee eeeeeeeee eeeeeeeeee eee eeeeeeeeeeee ee eeeeeeeeeee (ee. 888 eM ee eeeeeee eee eeeeeee), eeeeeee eeee M8M (888 eM), eee eeeeeee eeeeeeeee eeee Me8M (8 × 88 eM). Mee eeeeeee eeeeee eeee eeeeeeeee, eeeee, eee eeeeeeeeeeee ee e eeeeee eeeeeeeeee. Mee eeeee eeeeeee eeee eeeeeeee eee eeeeeeee ee eeeeeeeeeeee; eeeee: 8.8 e (88%); ee 888–888°M/88 Meee; (M/M) 88.8:8.8 (ee MM, 88% Meeeeeee eeeeee, 8 e, 888°M).

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) 88/8, 888.