Organolithium reagents nucleophilic addition reactions

Oxazolidinone-Substituted Carbanions. Oxazolidinone-substituted organostannanes readily undergo transmetalation with alkyllithium reagents to the organolithium derivatives which then can undergo nucleophilic addition reactions. -Substituted oxazolidinones can act in this capacity as both a nitrogen source and source of chirality (eq 60). Although the a-stereoselection... 

In general, nucleophilic addition reactions using Grignard or organolithium reagents to -chiral or other remotely chiral ketones usually yield mixtures of stereoisomers which are not synthetically use-fiil.9,12-27 However, some specific examples of stereoselective organolithium and Grignard additions to these remotely chiral carbonyl compounds have been reported. 

Another recent contribution [15] by Denmark et al. demonstrates an effective method for promoting the nucleophilic addition reactions [2] of organolithium reagents to imines. 

The chromium complex 46 of benzaldehyde imine is also a good substrate for asymmetric conjugate addition of organolithium reagents, where the reaction was mediated by a stoichiometric amount of chiral diether 18 in toluene to give, following propargylic electrophile incorporation, the cyclohexadienal 48 in up to 93% ee (Scheme 13) [38]. SAMP [(S)-l-amino-2-(methoxymethyl)pyrrolid-ine] hydrazones were used effectively in diastereoselective nucleophilic additions to (arene)Cr(CO)3 complexes [39]. 

Scheme 7.4 illustrates some of the important synthetic reactions in which organolithium reagents act as nucleophiles. The range of reactions includes S/v2-(ype alkylation (Entries 1 to 3), epoxide ring opening (Entry 4), and formation of alcohols by additions to aldehydes and ketones (Entries 5 to 10). Note that in Entry 2, alkylation takes place mainly at the 7-carbon of the allylic system. The ratio favoring 7-alkylation... 

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]. 

The most important application of organolithium reagents is their nucleophilic addition to carbonyl compounds. One of the simplest cases would be the reaction with the molecule CO itself, whose products are stable at room temperature. Recently, it was shown that a variety of RLi species are able to react with CO or f-BuNC in a newly developed liquid xenon (LXe) cell . LXe was used as reaction medium because it suppresses electron-transfer reactions, which are known to complicate the reaction . In this way the carbonyllithium and acyllithium compounds, as well as the corresponding isolobal isonitrile products, could be characterised by IR spectroscopy for the first time. 

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