Three-component reactions alkene termination

The three-component reaction of bis(phenylthio)-(trimethylsilyl)methyl lithium (243), phenyloxirane and a terminal alkene yields cyclopropanes 245142 (equation 82). It is assumed that a-elimination of LiSPh from the carbenoid-like species 243 generates phenylthio(trimethylsilyl)carbene (244) which is in equilibrium with 243 although this equilibrium is probably far on the side of the latter, trapping of the thiophenolate ion by the... 

When the addition of the aldehyde is postponed, the in situ generated phosphonium ylide will undergo a Michael addition to the electron-deficient alkene followed by proton transfer to generate another phosphonium ylide (Scheme 23). Based on these transformations, Tian et al. have developed a one-pot, stepwise, three-component reaction of aldehydes, a-haloacetates, and terminal alkenes in the... 

Scheme 23 One-pot, stepwise, three-component reaction of aldehydes, a-haloacetates, and terminal alkenes...

In this context, an elegant alkylative carbonylation of alkenes accompanied by phenylselenyl transfer is described by Ryu and Sonoda. This three-component coupling involves the addition of a methoxycarbonylmethyl radical to an alkene, the trapping of the produced alkyl free radical by CO, and termination of the reaction by phenylselenenyl group transfer from the starting material. Yields are... 

Another useful reaction for the difunctionalization of olefins involves a group transfer carbonylation starting from a a-(phenylseleno)carbonyl (or related derivatives) and a terminal alkene under 80 atm of CO. An alkyl radical is first formed by the photocleavage of a C-SePh bond. The addition of this radical to the olefin, followed by the incorporation of CO and radical coupling with PhSe-, gave substituted selenoesters via a three-component coupling reaction [74], The intermolecular formation of C—C bonds via phenylseleno group transfer has been likewise adopted in the reaction between ester-substituted O,Se-acetals and an olefin [75],... 

Ryu, Sonoda and co-workers reported a three component coupling reaction, based on group transfer carbonylation, that involves methyl a-(phenylseleno)-acetate 63 (and related derivatives), terminal alkenes, and CO (Scheme 18) [93]. 

Reddy and collaborators reported a new one-pot, three-component procedure toward the synthesis of novel 4-phenyl-2-[3-(alkynyl/alkenyl/aryl) phenyl] pyrimidine libraries starting with the Michael addition of enaminone 64 with 3-bromobenzimidamide hydrochloride (65) (Scheme 28) (13S75). This was followed by a cyclization, an isomerization, a dehydration, and a subsequent Sonogashira reaction with terminal alkynes or a Suzuki reaction with arylboronic acids or a Heck coupling reaction with alkenes. 

Very recently, Jiang et al. developed a palladium-catalyzed three-component coupling reaction for the synthesis of 1,3-butadienes that involves the sequential formation of a C(sp )—C(sp ) bond and a C(sp )- (sp ) bond from a benzyl chloride, a terminal alkyne, and a monosubstituted alkene [32],... 

Secondary alcohols have been prepared through a three-component coupling reaction catalyzed by a gold compound (Scheme 2.7) [8]. In addition to the boronic acid and water, the third component of the coupling reaction was an unactivated terminal alkene. 

The Imhof group demonstrated a three-component coupling reaction of a, -unsaturated imines with CO and alkenes catalyzed by Ru3(CO)j 2, which produced a,a-disubstituted, y-unsaturated y-butyrolactams [62]. Similar reactions were also independently explored by Chatani and coworkers (Eq. (7.53)) [63]. Ethylene, vinylsilane, and norbornene could be used as the alkene partners, but the terminal alkenes were not compatible with the reaction system. The imine substrates bearing electron-withdrawing group showed low reactivity. 

Bhuvaneswari et al. [75] reported a copper-catalyzed three-component couphng of arynes, terminal alkynes, and activated alkenes, providing l-alkyl-2-alkynylben-zenes 108 (Scheme 5.72). 2-(Trimethylsilyl)-3,4-dimethylphenyl triflates 107 were used as benzene precursors. Reaction of terminal alkynes with Cu(l) species in the presence of CsF (or K COj) gives copper acetylides A. Alkynylcupration of the in situ-generated arynes B with cuprous acetylides A affords arylcuprous intermediates... 

A major difficulty with the Diels-Alder reaction is its sensitivity to sterical hindrance. Tri- and tetrasubstituted olefins or dienes with bulky substituents at the terminal carbons react only very slowly. Therefore bicyclic compounds with polar reactions are more suitable for such target molecules, e.g. steroids. There exist, however, several exceptions, e. g. a reaction of a tetrasubstituted alkene with a 1,1-disubstituted diene to produce a cyclohexene intermediate containing three contiguous quaternary carbon atoms (S. Danishefsky, 1979). This reaction was assisted by large polarity differences between the electron rich diene and the electron deficient ene component. 

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