Michael addition of nucleophile

The Michael addition of nucleophiles to the carbon—carbon double bond of maleimide has been exploited ia the synthesis of a variety of linear polymers through reaction of bismaleimide with bisthiols (39). This method has been used to synthesize ethynyl-terminated imidothioether from the reaction of 4,4 -dimercaptodiphenyl ether [17527-79-6] and A/-(3-ethynylphenyl)maleimide (40). The chemical stmcture of this Michael addition imide thermoset is as follows ... 

The (formal) Michael addition of nucleophiles to thiirene oxides and... 

The Michael addition of nucleophiles to a,/J-unsaturated sulfoxides creates initially a-sulfmyl carbanions by nucleophilic attack on the /J-carbon atom. Russell and Becker157 found that treatment of a mixture of diphenylmethane and anisaldehyde with potassium t-butoxide in DMSO gave at first the condensation product 170, which upon Michael addition afforded the final product 171. 

Barrett and coworkers have explored hetero-substituted nitroalkenes in organic synthesis. The Michael addition of nucleophiles to 1-alkoxynitroalkenes or 1-phenylthionitroalkenes followed by oxidative Nef reaction (Section 6.1) using ozone gives a-substituted esters or thiol esters, respectively.41 As an alternative to nucleophilic addition to l-(phenylthio)-nitroalkenes, Jackson and coworkers have used the reaction of nucleophiles with the corresponding epoxides (Scheme 4.4).42 Because the requisite nitroalkenes are readily prepared by the Henry reaction (Chapter 3) of aldehydes with phenylthionitromethane, this process provides a convenient tool for the conversion of aldehydes into ot-substituted esters or thiol esters. 

The IMDAF (intramolecular Diels-Alder furan) precursors 492 were prepared via Michael addition of nucleophiles possessing an unsaturated tether 491 to furoyl nitroalkene 490. Furyl nitroalkene 490 was prepaperd via the nitroaldol (Flenry) reaction. Compound 492 was heated in appropriate solvent such as toluene, xylene, etc., to provide the IMDAF cycloadducts 65 and 66 (Table 16) <2005JOC2235>. 

Exploiting the known reactivities of chlorocyclopropylideneacetates 1 -3, the synthesis of a compound library from polymer-bound chlorocyclopropylidene-acetic acid 1-H has been realized in a sequence of transformations as shown in Scheme 77 [127], following attachment of the acid 1-H to a resin (A), a Michael addition of nucleophile (B), nucleophilic substitution of the chlorine (C), modification of one of the substituents (D) and cleavage of the substrate to polymer bond (E). 

The Michael addition of nucleophiles to coumarins catalyzed by solid bases provides an interesting approach to the synthesis of 4-substituted 3,4-dihydrocumarins, because with the conventional Michael catalysts the alkaline hydrolysis of the 8-lactone predominates (Scheme 44). Results were obtained when the Michael addition of diethyl malonate to coumarin was catalyzed by the activated Ba(OH)2 292). An unusual 1,2-addition-elimination process at the C = 0 bond was observed. The mechanism of this reaction was explained on the basis of the microcrystalline structure of the catalyst. It was suggested that the rigid coumarin molecule interacts with the Ba ions through the lone-pair electrons of both oxygen atoms of the... 

The typical reaction is Michael addition of nucleophiles thus, 1-vinylpyridinium ion (967) adds A-, S- and C-nucleophiles to give products of type (968). A-Vinyl groups can also undergo polymerization. 

The Michael addition of nucleophiles on oc,P-unsaturated electron withdrawing groups, often carbonyl-containing functional groups, is a widely used reaction for the formation of C—C or C—heteroatom bonds. When the Michael acceptor bears a substituent on the a-position to the carbonyl, then an asymmetric carbon is created upon protonation of the transient enolate generated by the nucleophilic addition (Scheme 7.9). 

Allylic and dienyl sulfones have been prepared by conjugate addition to 1,3-dienes ". Phenylsulfonyhnercuration of conjugated dienes gives mercury adducts which can be treated with base to afford phenylsulfonyldienes. 2-(Phenylsulfonyl)-l,3-dienes can be stereo- and regioselectively functionalized via Michael addition of nucleophiles to give allylic sulfones. A key intermediate in the synthesis of a Monarch butterfly pheromone 4 was prepared by BackvaU and Juntunen by alkylation and subsequent palladium-catalyzed substitution of the allylic sulfone formed by Michael addition of dimethyl malonate to 2-(phenylsulfonyl)-l,3-butadiene (equation 10). 

Sakaklbara and co-workers have reported in full (c,f. Vol.16, p.ll2) on the synthesis of, and Michael addition of nucleophiles to, the anomerlc methyl 2,3-dldeoxy-2-nitro-3-D-erythro-hex-2-eno-pyranosldes (18) and (19). In the case of the B-anomer (18), nucleophiles added predominantly in an equatorial fashion at C-3,... 

Pyrolysis of aryl sulphoxides gives rise to alkenes. Coupled with Michael addition of nucleophiles to aryl vinyl sulphoxides, a rather general synthesis of substituted alkenes results. Annulenophanes have been prepared by photolytic triethyl phosphite-induced desulphurization of cyclic bis-dialkylsulphides. ... 

Double bonds being part of hetero-Cope systems can be generated by Michael addition of nucleophiles to electron-poor carbon-carbon triple bonds. 

Nitro- 1-phenylthioalkenes (1), on reaction with teri-butyl hydroperoxide, are converted into epoxides and these species react with nucleophiles (halide salts, horon trifluoride etherate, trifluo-roacetic acid, MsOH) to provide a-substituted phenylthio esters (eq 3). Alternatively, Michael addition of nucleophiles (aUcox-ides, Phth, Ts, malonate) to 1-nitro-l-phenylthioalkenes and ozonolysis of the intermediate nitronate gave similar adducts (eq 4), including a-amino and a-hydroxy acid derivatives. ... 

Among the most successful catal)rtic systems employed in enantioselective nickel-catalysed Michael additions of nucleophiles to nitroalkenes is that developed by Evans and Seidel in 2005, which allowed enantioselectivities of up to 95% ee to be achieved in the enantioselective conjugate additions of 1,3-dicarbonyl compounds to nitroalkenes (Scheme 2.3). Products resulting... 

Michael addition of nucleophiles to the nitro-(phenylthio)alkene (61) provided, after ozonolysis of the intermediate nitronates, substituted phenylthiol esters (62) with good to excellent diastereoselectivity. They were converted to derivatives (63) of methyl L-alluronate by treatment with methanolic mercury(II) acetate. ... 

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