Wittig olefination reaction

The reaction of an alkylidene phosphorane 1 (i.e. a phosphorus ylide) with an aldehyde or ketone 2 to yield an alkene 3 (i.e. an olefin) and a phosphine oxide 4, is called the Wittig reaction or Wittig olefination reaction. ... 

The Witting reaction has been investigated in aqueous conditions.305 Wittig olefination reactions with stabilized ylides (known as the Wittig-Homer or Homer-Wadsworth-Emmons reaction) are sometimes performed in an organic/water biphase system.306 Very often, a phase-transfer catalyst is used. Recently, the use of water alone as solvent... 

With the fully functionalized heterocyclic core completed, synthetic attention next focused on introduction of the 3,5-dihydroxyheptanoic acid side-chain. This required initial conversion of the ethyl ester of 35 to the corresponding aldehyde through a two-step reduction/oxidation sequence. In that event, a low-temperature DIBAL reduction of 35 provided primary alcohol 36, which was then oxidized to aldehyde 37 with TRAP. Subsequent installation of the carbon backbone of the side-chain was accomplished using a Wittig olefination reaction with stabilized phosphonium ylide 38 resulting in exclusive formation of the desired -olefin 39. The synthesis of phosphonium ylide 38 will be examined in Scheme 12.5 (Konoike and Araki, 1994). 

The lactol 68 undergoes ring opening via a Wittig olefination reaction to afford the product 69 (Equation 12) <2004JA5493>. 

Maryanoff, B.E. and Reitz, A.B. (1989) The Wittig olefination reaction and modifications involving phosphoryl-stabilized carbanions. Stereochemistry, mechanism, and selected synthetic aspects. Chemical Reviews, 89(4), 863-927. 

The primary alcohol is first oxidized to an aldehyde, which is then the substrate in a Wittig olefination reaction. Here a stabilized ylide is employed and therefore the E double bond is formed exclusively. (For a detailed description of the Wittig reaction see Chapter 13 the selectivity issues are explained in Chapter 9.)... 

Wittig olefination reaction ( the phosphorus way ) has been a very popular reaction in organic synthesis. However, it is now in competition with Peterson/Chan olefination reaction327 ( the silicon way ). Formally, this latter involves the formation of a (3-silyl heteroatomic anion, which in the absence of an electrophile undergoes a (3-shift of the silyl moiety to the heteroatom (usually oxygen) with final elimination of silylated heteroatomic anion and formation of the olefin. 

Several variants of the Wittig olefination reaction have been adapted to solid phase (Fig. 8). Williard et al. [43] prepared a series of stilbenes using the Homer-Emmons reaction on resin-bound aldehydes. A route to either substituted or unsubstituted unsatu-... 

B. E. Maryanoff, A. B. Reitz, The Wittig Olefination Reaction and Modifications Involving Phospho-rylstabilized Carbanions. Stereochemistry, Mechanism, and Selected Synthetic Aspects, Chem. Rev. 1989, 89, 863-927. 

P. J. Murphy, J. Brennan, The Wittig Olefination Reaction with Carbonyl Compounds Other than Aldehydes and Ketones, Chetn. Soc. Rev. 1988, 17, 1-30. 

Performing Wittig olefination reactions in an intramolecular manner on difunctional starting compounds has several advantages over intermolecular variants ... 

Phosphoranium salts have been shown to be very useful reagents in the Wittig olefination reaction The formation proceeds easily both when alkylphosphanes and arylphosphancs are utilized as reagents-... 

The Wittig olefination reaction, the modifications, and the nature of the organophosphorus intermediates has been reviewed. ... 

The reaction of triphenyl-/5-phosphanes with carbonyl compounds, the Wittig olefination reaction, involves addition to the carbonyl carbon in a reaction closely related to the aldol condensation. Triphenyl-25-phosphanes, derived from alkyltriphenylphosphorus salts, react with 1,1,1-trifluoroacetonc33 or other trifluoromethyl ketones34-35 to give products 29. 

A review on the chemistry of thio derivatives of trivalent phosphorus acids which covers the literature to 1986, includes a section on pentaco-ordinate phosphorus compounds derived from addition to a-diketones and unsaturated systems activated to nucleophilic attack by electron withdrawing groups. Chemical bonding in hypervalent molecules has been discussed and qualitative bonding concepts developed to supersede the dsp and d sp models. A review on the mechanism and stereochemistry of the Wittig olefination reaction inevitably includes a discussion of the equilibrium between betaine and 1,2-oxaphosphetane intermediates. A correction has been published to reference 19 of Chapter 2 in SPR14, Vol.21, concerning the Mitsunobu Reaction. ... 

Murphy, P J, Brennan, J, The Wittig olefination reaction with carbonyl compounds other than aldehydes and ketones, Chem. Soc. Rev., 17, 1-30, 1988. 

The hemiacetal opens after deprotonation to give the alcohol at C-7 and the aldehyde at C-8. This can undergo a Wittig olefination reaction with a very good E Z ratio of >15 1. 

Mari, F., Lahti, P. M., McEwen, W. E. Molecular modeling of oxaphosphetane intermediates of Wittig olefination reactions. Heteroatom Chem. 1990, 1,255-259. 

---