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Organolithium conjugate addition

The reaction of butyllithium with 1-naphthaldehyde cyclohexylimine in the presence of (/C )-l,2-diphenylethane-1,2-diol dimethyl ether in toluene at —78 °C, followed by treatment with acetate buffer, gave 2-butyl-1,2-dihydronaphthalene-l-carbaldehyde, which was then reduced with sodium borohydride in methanol to afford (1 R,2.S)-2-butyl-1 -hydroxymcthyl-1,2-dihydronaphthalene in 80% overall yield with 91 % ee83. Similarly, the enantioselective conjugate addition of organolithium reagents to several a,/J-unsaturated aldimines took place in the presence of C2-symmetric chiral diethers, such as (/, / )-1,2-butanediol dimethyl ether and (/, / )- ,2-diphenylethane-1,2-diol dimethyl ether. [Pg.909]

The conjugate addition substrate that we were considering bore an obvious resemblance to Stork s however, it would incorporate a free NH and OH, as well as a more sensitive aldehyde. In this light, an approach involving reactive organolithium species seemed unlikely to be successful, and a few experiments quickly validated this surmise. We therefore sought a precursor that could... [Pg.93]

However, diphenyl cyclopropenone undergoes conjugate addition via C1(2) with organolithium reagents227,228 as indicated by products of structure 337 and 338 ... [Pg.77]

Organolithium compounds are highly reactive and have been used in a variety of organic transformations. A major problem in the development of catalytic asymmetric conjugate additions of organolithium reagents to a,/3-unsaturated carbonyl compounds is that the high reactivity of RLi may cause both low chemoselectivity (1,2- vs. 1,4-addition) and low enantioselectivity. [Pg.370]

In addition to the reactions discussed above, a,//-unsaturated oxazolines can also act as chiral electrophiles to undergo conjugated addition of organolithium reagent to give optically active / ,/ -disubstituted carboxylic acids.52 The vinyl oxazolines 48 are prepared using the two methods outlined in Scheme 2-27. [Pg.93]

Whereas, the sulfur ylide 9 undergoes conjugate addition to enones thereby precluding 1,2-cyclopentyl annulation, the organolithium 37a undergoes clean carbonyl addition. Cyclopentenone participates smoothly in this sequence (Eq. 88)81>. [Pg.55]

Complexation of enones with MAD can be used to effect conjugate additions with organolithium reagents. This unusual 1,4-selectivity is observed mainly with cyclic systems and requires 2 equiv. of the aluminum reagent as well as of the nucleophile for full effect. [Pg.207]

The chemical behavior of heteroatom-substituted vinylcarbene complexes is similar to that of a,(3-unsaturated carbonyl compounds (Figure 2.17) [206]. It is possible to perform Michael additions [217,230], 1,4-addition of cuprates [151], additions of nucleophilic radicals [231], 1,3-dipolar cycloadditions [232,233], inter-[234-241] or intramolecular [220,242] Diels-Alder reactions, as well as Simmons-Smith- [243], sulfur ylide- [244] or diazomethane-mediated [151] cyclopropanati-ons of the vinylcarbene C-C double bond. The treatment of arylcarbene complexes with organolithium reagents ean lead via conjugate addition to substituted 1,4-cyclohexadien-6-ylidene complexes [245]. [Pg.36]

RCuCNLi (25-62%)]. Successful conjugate addition required the activating influence of TMSCl [11c], and rather modest yields (25-64%) were obtained with dialkyl-substituted 2-enones. Cuprate preparation directly from the organolithium... [Pg.116]


See other pages where Organolithium conjugate addition is mentioned: [Pg.396]    [Pg.396]    [Pg.121]    [Pg.728]    [Pg.728]    [Pg.892]    [Pg.907]    [Pg.1029]    [Pg.291]    [Pg.283]    [Pg.197]    [Pg.686]    [Pg.694]    [Pg.1336]    [Pg.109]    [Pg.370]    [Pg.370]    [Pg.373]    [Pg.471]    [Pg.477]    [Pg.16]    [Pg.70]    [Pg.281]    [Pg.107]    [Pg.121]    [Pg.129]    [Pg.224]    [Pg.225]    [Pg.197]    [Pg.121]    [Pg.129]    [Pg.224]    [Pg.225]    [Pg.321]    [Pg.902]    [Pg.903]    [Pg.923]   
See also in sourсe #XX -- [ Pg.269 , Pg.307 ]




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Asymmetric conjugate addition organolithium reagents

Conjugate addition organolithium reagents

Conjugate addition reactions organolithium reagents

Conjugated compounds, 1,2-addition with organolithium reagents

Organolithium compounds conjugate additions

Organolithiums addition

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