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24.2.11.1.4.2 Variation 2: Wittig and Horner–Emmons Reactions

DOI: 10.1055/sos-SD-024-00481

Dölling, W.Science of Synthesis, (200624474.

Phosphorus ylides such as trialkoxy-,[‌73‌,‌97‌‌99‌] tributyl-,[‌100‌,‌101‌] or triphenylphosphoranes[‌95‌,‌102‌‌105‌] have been extensively used for the preparation of 2-alkylidene-1,3-dithiolanes[‌95‌,‌99‌] and -1,3-dithianes,[‌73‌,‌97‌,‌98‌,‌105‌] and their acyclic analogues.[‌100‌,‌101‌,‌103‌‌105‌] Reactions of 2-chloro-1,3-dithiane with triphenylphosphine or triethyl phosphite proceed smoothly at room temperature affording the corresponding triphenylphosphonium chlorides or diethyl phosphonates, respectively, in good yields. Both are excellent precursors for the preparation of ketene S,S-acetals; once deprotonated they may be reacted with aromatic aldehydes at 0°C and with aliphatic aldehydes at room temperature to give the corresponding ketene S,S-acetals. Three examples depicting the value of the traditional Wittig alkenation are shown in Scheme 19. In the first, 2,2-ethane-1,2-diylidenebis(1,3-dithioles) 47 are obtained by the reactions of aldehydes 45 with the phosphoranes 46,[‌100‌,‌101‌] and in the second, 1,3-dithiolan-2-yl(triphenyl)phosphonium tetrafluoroborate (48) is the precursor that provides 2-alkylidene-1,3-dithiolanes 49.[‌95‌] In the third illustration, triphenylphosphonium salts 50 are similarly used to yield 2-alkylidene-1,3-dithianes 51.[‌102‌]

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Mee MeeeeeMeeeee eeeeeeeeee eeeee eeeeeeeeeeee 88, ee eeeeeeeee eee eeeeeeee, eeeeeee eee eeeeee eeeeeeeee eee eeeeeee, eeeeeee eeeeee M,M-eeeeeee 88 ee eeee eeeeee eee eeeeee eeee eeeee eeee 88 ee 88% (Meeeee 88).[‌888‌] Meee eeeeee eeeeeeeeee ee eee eeeeeeee eeeeeeeee eeee eeeee M,M-eeeeeee eee eeeeeeeeeee ee eeeeeeeeeee, eee eee eeee eeee eee eeeeeeeeee eee eeeee-eeeeeee, ee eeee eeeeeeeee ee eeeeeeee eeee eeeeeeeeee. Mee eeeeeeeeee eeeeeeee eeeeeeeee eeee eeee ee eeeee eeee [eeeeeeeeeeee (Meeeee M),[‌888‌,‌888‌‌888‌] eeeeee eeeeeee (Meeeee M),[‌888‌] ee eeeeee eeeeeeeee eeeee eeeee-eeeeeeee eeeeeeeeee (Meeeee M),[‌888‌]] ee eeee eee eee eeeeeeeeee ee eee eeeeeeeeeeee eeeee. Mee eeeeeeee eeeeeeeee 88 eee eeeeeeeeee eeeeee eee eee ee eeeeeee eeeeeeee ee eeee eeeeee ee eee Meeeeee eeeeeeee eeeeeee e eeeeeeee eeeeeeeee eee e eeeeee M,M-eeeeee, ee ee eee Meeeeeee-eeee eeeeeeee ee ee α-eeeeeeeeeeeeee eeeeeeeee eeee ee eeeeeee ee eee eeeeeeee ee eeeeee.

Meeeee 88 Meeeee M,M-Meeeeee ee eee MeeeeeMeeeee Meeeeeeeee ee Meeeeeeee eee Meeeeee[‌888‌,‌888‌‌888‌]

Meeeeeeeeee 88

M8 M8 M8 M8 Meeeee Meeee (%) ee 88 Mee
M M Me Me M 88 [‌888‌]
Me M Me Me M 88 [‌888‌]
Me Me Me Me M 88 [‌888‌]
(MM8)8 Me Me M 88 [‌888‌]
Me Me Me Me M 88 [‌888‌]
Me M Me Me M 88 [‌888‌]
8-MeM8M8 M Me Me M 88 [‌888‌]
Me Me Me Me M 88 [‌888‌]
Me Me (MM8)8 M 88 [‌888‌]

Meeeeeee ee ee eeeeee eee eee eeeeeeeee ee eeeeeee eeeeeeeee, eee MeeeeeMeeeee eeeeeeee eeeee eeeeeeeeeeee eeee eee eee eeeeeeeeeee ee 8-eeeeeeeee-8,8-eeeeeeeee eee eeeeeee eeeeeeeee eeeeeeeeee 8,8,8-eeeeeeeee, eee 8,8-eeeeeeeeeeeee eeeee; ee eeeeeeeeee, eee eeeeee ee eeeeeee eeeeeeeee eeeeeeeeeeeeeeeeeee ee eeeee eeee eee eeeeeeeeee eeeeeeeeeee eeeee eee Meeeee eeeeee. Me e eeeeeeee eeeeeee, 8-eeeeeeeeeeeeeee-8,8-eeeeeeeee eee ee eeeeeeee ee eeeeee eeeeeeeeeeee eeeeee eeee eeeeeeeeeeeee eee eeeeeee 8,8-(eeeeeee-8-ee)eeeeeeeeeeee eeeee eeeeeeeeeeee ee eee eeee.[‌888‌] 8,8-Meeeeeeeeeeeee eeeeeee eeee-8-eeeeeeeeeeeeeeee eee ee eeeeeeeeeee ee eee MeeeeeMeeeee eeeeeeeee eeee eeeeeeeeeee M,M-eeeeeee ee eeeeee eeee 88 ee 88%,[‌888‌] eee eeeeeee (8,8-eeeee-8λ8,8λ8-8,8-eeeeeee-8-ee)eeeeeeeeeeee eee ee eeeeeeeeeeee eeee eeeeeee eeeeeeeee, eee eeeeeeeeeee eeee eeeeeeeee ee eeee 8-eeeeeeeeee-8,8-eeeeeeee 8,8-eeeeeeee ee eeeeee ee 8888%.[‌888‌]

Meeeeeeeeeee Meeeeeeee

Meeeeeeeeee Meeeeeeeeeeeeee-8,8-eee(8,8-eeeeeeee)eeeeeeeeeeeeeeee (88, M8=M8=MM8Me):[‌888‌,‌888‌]

Meeeee Me8M (8.8eM) eee eeeee ee 8,8-eee[(eeeeeeeeeeeeeee)-8,8-eeeeeee-8-ee](eeeeeeee)eeeeeeeeeee eeeeeeeeeeeeeeeee (88; 888ee, 8eeee) eee 8-(eeeeeeeeeeeeeee)-8,8-ee(eeeeeeeeeeeeeee)-8,8-eeeeeeee (88; 888ee, 8eeee) ee MMM (88eM) eeeeeeeeee ee ee. Mee eeeeeee eee eeeeeee eee 8e eee eeee eeeeeeeeeeee, eee eee eeeeeee eee eeeeeeeeeeeeeee (eeeeee eee, MM8Me8) ee eeeeee eeeeee eeeeeeee; eeeee: 888ee (88%).

8-Meeeeeeeee-8,8-eeeeeeeee 88; Meeeeee Meeeeeeee:[‌888‌]

88% MMM8 (8.8e, 88eeee) eee eeeee eeee eeeeeeee eeeeee ee. 88eee ee 8-eeeeee-8,8-eeeeeeee (8.8e, 88eeee) eee Me8M (8.8e, 88eeee) ee MMM (88eM) eeeeeeeeee ee 88°M. M eeeeeeeee eeeeeeeeeee eeeeeeee eeeeeeeeeee, eee eee eeeeeee eee eeee eeeeeee ee eeee ee ee eee eeeeeee eee 88eee, eeeeee Me8M (88eM) eee eeeee. Mee eeeeeeeeeee ee 8,8-eeeeeee-8-ee(eeeeeeeee)eeeeeeeeeee eeeeeeeeeeeeeeeee eee eeeeeeeee ee eeeeeeeeee, eee eeeeee eeeeeeeeee eeee eeeee Me8M; eeeee: 8.8e (88%); ee 888888°M (MeMM ee MMMe8).

8.88M MeMe ee eeeeee (8eM, 8.8eeee) eee eeeee ee e eeeeeee eeeeeeeeee ee 8,8-eeeeeeeee-8-eeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeee (8.8e, 8.8eeee) ee MMM (88eM) eeee ee 88°M eeeee M8. Meeeeeee eee eeeeeeeee eee 8eee ee eeee eeeeeeeeeee ee eeee e eeeeee eeee ee eeeee eee eeeeeeee (8.8eeee) ee MMM (8eM) eee eeeee, eee eee eeeeeee eee eeee eeeeeee ee 88°M eee 8eee, eee ee ee eee 8e. Me eee eeeeee eeee 88% ee MM8Me (888eM), eee eee eeeeeee eee eeeeeeeee eeee Me8M (8×88eM). Mee eeeeeeee eeeeeeee eeee eeeee (MeMM8), eeeeeeee, eee eeeeeeeeee ee eeeee eee eeeee eeeeee M,M-eeeeee, eeeee eee eeeeeee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, MMMe8).

Meeeee M,M-Meeeeee 88; Meeeeee Meeeeeeee:[‌888‌]

Meeeee M: MeMe (8.888eee) ee eeeeee eee eeeee ee 88°M eeeee ee eeeee eeeeeeeeee ee e eeee ee eee eeeeeeeeeee 88 (8.88eee) ee MMM (88eM). Mee eeeeeee eee eeeeeee ee 88°M eee 8.88e, eeee eee eeeeeeee eeeeeeee (8.88eee) ee MMM (88eM) eee eeeee eeeeeeee ee 88°M, eee eee eeeeeee eee eeeeeee eee 88eee ee eeee eeeeeeeeeee. Meeee eeeeeee ee eee eeeeeeee, eee eeeeeee eee eeeeeeeeeee ee MMMe8 (88eM), eee eee MMMe8 eeee eee eeeeee eeee ee MM8Me, eee eeee eeee M8M. Meeee eeeeee eee eeeeeeeeeee, eee eeeeeee eeeeeeee eee eeeeeeee ee eeeeeeeeeeee, ee eeeeeeeeeeeeeee, ee ee eeeeee eeeeeeeeeeeeee.

Meeeee M: M 88% eeeeeeeeee ee MeM ee eeeeeee eee (8.88e, 8.888eee), eee eeeeee eeeee eeeee eeee eeeeeeeee eeeee (8×), eee eeee eeeee ee e eeee ee eee eeeeeeeeeee 88 (8.88eee) eee eee eeeeeeee eeeeeeee (8.88eee) ee MMM (88eM) (eeee MeMMM eee eeeeeeee eee eeeeeeee eeeee 8e ee ee, eee ee eee eeee ee eeeeeee, eee eeeeeee eee eeeeee ee 88°M eee 8e). Meeee eeeeeee ee eee MMM eeeee eeeeeee eeeeeeee, eee eeeeeee eee eeeeeeeeeee ee MMMe8 (88eM). Mee MMMe8 eeeee eee eeeeee eeee ee MM8Me eee eeee eeee M8M, eeeee, eee eeeeeeeeeeee ee eeeeee eee eeeee eeeeeee, eeeee eee eeeeeee eeeeeeee ee eeeeeeee eeeeeee.

Meeeee M: Mee eeeeeeeeeee 88 (8.88eee) eee ee eeeeeeee eeeeeeee (8.88eee) ee MM8Me8 (8eM) eee eeeee ee e eeeeeeeeeeeee eeeeeee ee 88% ee MeMM (88eM) eeeeeeeeee MMMMM (8.8e) eee MM8Me8 (8eM). Mee eeeeeee eee eeeeeee eee 8.8e ee ee, eee eeeeeeeeee MM8Me8 (88eM) eee eeee eeeee. Mee eeeeeee eeeee eee eeeeee eeee ee MM8Me eee eeee eeee M8M, eeeee, eee eeeeeeeeeeee ee eeeeee eee eeeee eeeeeee.

References


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