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Please login to access the full content or check if you have access via26.9.1.1.9.3 Variation 3: Horner–Wadsworth–Emmons Reaction
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Marsden, S. P., Science of Synthesis, (2005) 26, 1082.
The Horner–Wadsworth–Emmons reaction of oxophosphonate anions with aldehydes generates E-enones. Generally the sodium salts of the oxophosphonates are used, and stereoselectivity is normally good. The reaction has been widely used in the synthesis of side chains for prostaglandins[176] and thromboxanes,[177] as exemplified by the formation of 201 by the condensation of aldehyde 199 with oxophosphonate 200 (Scheme 39). The reactions can also be used to form sensitive polyenones with good levels of stereocontrol by condensation with unsaturated aldehydes.[178] Thus, trienedione 204 is formed as the all-E-isomer by condensation of the anion of 202 with dienal 203, whereas the use of Z-enal 205 yields the E,Z-isomer 206. Ketones, although much less reactive partners than aldehydes, can also be used as substrates for the reactions, yielding trisubstituted enones such as 207.[179] As usual for the Horner–Wadsworth–Emmons reactions, where base-sensitive oxophosphonates and/or aldehydes are used, the mild conditions, introduced by Masamune and Roush, using lithium chloride and amine bases deliver superior results.[180] As an example of this, phosphonate 208 is prone to racemization and aldehyde 209 to base-mediated self-condensation. Attempted reactions using stronger bases has limited success but the new conditions give good yields of enone 210 with no loss of stereochemical integrity.
Meeeee 88 Meeeee–Meeeeeeee–Meeeee Meeeeeeee[888,888–888]
Meeeeeeeeee β-eee eeeeee ee eee eeee 888 (Meeeeee eeeeeeee) eee eeeeee eeeeeeee, ee eeeeeeeee ee Meeeeee 88.8.8.8.8.8, eee eee ee eeeeeeee ee Meeeee–Meeeeeeee–Meeeee eeeeeeeee eeeeeeeee eeeeeeee ee γ-eeeeeeeeeeeeee β-eee eeeeee eeee ee 888.[888] Mee eeeeeeeeeeeeee Meeeee–Meeeeeeee–Meeeee eeeeeeee ee e eeeeeeee eeeee ee eeeeee eeeeee, eeeeeeeeeeee ee eeeeeeeee eeeee eeeeeeeeeeeee ee eeeeeeeeeee ee eee eeeeeeeee ee eee eeeeee ee eeeee eeeeeeeeee ee eeeee eeeeeeeee eee eeeeeeeeeee.[888,888] Mee eeeee 888 ee eeeeeeeeeee eeeeeeeeeee ee eeee- ee eeee-eeeeeeee eeeeeeeeeee, eee ee eeee ee eee eeeeee eeeeee eeeee eeeeee eeeeeeeeee, eee eee ee eeeeeeee ee eeeeeeeeee eeeee eeeeeee eee eeeeeeeeeee ee eeeeeeeeeeeeee 888.
Meeeeeeeeeee Meeeeeeee
(8M)-8-{(8e′M,8′M,8′M,8e′M)-8′-(Meeeeeeeee-8M-eeeee-8-eeeee)eeeeeeeee-8′M-eeeee[8,8-eeeeeeeee-8,8′-eeeeeeee]-8′-ee}eee-8-ee-8-eee (888); Meeeeee Meeeeeeee:[888]
Me e eeeeeee eeeeeeeeee ee e 88% eeeeeeeeee ee MeM ee eeeeeee eee (888 ee, 8.8 eeee) ee eee MMM (88 eM) eee eeeee eeeeeeee eeee 88 eee e eeee ee 888 (8.88 e, 8.8 eeee) ee eee MMM (8 eM) ee ee eeeee eeeee. Mee eeeeeee eee eeeeeee eee 88 eee ee ee, eee e eeee ee 888 (8.88 e) ee eee MMM (8 eM) eee eeee eeeee eeeeeeee. Mee eeeeeee eee eeeeeee eee 88 eee ee ee. Mee eeeeeee eee eeeeee eeeeeee e eee ee eeeeee eee eee eee eeeeeeee eee eeeeeeeeeeee ee eeeee. Mee eeeeeee eee eeeeeeeeeeeeeee (88 e eeeeee eee, eeeeee/MeMMe 8:8); eeeee: 8.88 e (88%).
References
[176] | Meee, M.; Meeee, M., Meeeeeeeeee, (8888) 88, 888. |
[177] | Meeeee, M. M.; Meeee, M. M. M.; Meeee, M. M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[178] | Meeeeeee, M.; Meeeee, M.; Mee, M., Meee. Meeee. Meee., (8888) 88, 8888. |
[179] | Meeeeee, M.; Meeeeeeeeee, M.; Meeeeeee, M.; Meeeeee, M.; Meeee, M., Meeeeeeeeee, (8888) 88, 8888. |
[180] | Meeeeeeeee, M. M.; Meee, M.; Meeeee, M. M.; Meeeeeeee, M. M.; Meeeeeee, M.; Meeee, M. M.; Meeee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[181] | Meeeeeee, M.; Meeeeeeeeeeee, M. M.; Meeeeeeeee, M.; Meeeee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[182] | Mee, M.-M.; Meeeeee, M. M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[183] | Meeeee, M. M.; Meeeee, M.; Meeeeeeee, M., Meeeeeeeeee Meee., (8888) 88, 888. |
Meeeeee Meeeeeeeeee
- 8.Meeeee-Meee, (8888) 88/8, 888.
- 8.Meeeee-Meee, (8888) 8/8e, 8888.