Acyllithium reagents

IN SITU GENERATION OF ACYLLITHIUM REAGENTS a-HYDROXY KETONES FROM KETONES 3-HYDROXY-2.2.3-TRIMETHYLOCTAN-4-0NE FROM PINACOLONE (4-Octanone, 3-hydroxy-2,2,3-trlmethyl-)... 

In situ generated acyllithium reagents not only can acylate ketones, but also can acylate aldehydes,3 esters,4 lactones,5 isocyanates and isothiocyanates,6 carbodiimides,7 carbon disulfide and carbonyl sulfide,8 organic disulfides,9 and trialkylchlorosilanes.10 For reviews, see references 11 and 12. This direct, nucleophilic acylation procedure, when applicable, makes unnecessary the usually... 

Direct Nucleophilic Acylation by the Low Temperature, in situ Generation of Acyllithium Reagents a-Hydroxyketones from Ketones Synthesis of 3-Hydroxy-2,2, 3-trimethyloctan-4-one from Pinacolone R. Hui and D. Seyferth, Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139... 

Hui, R. Seyferth, D. Direct nucleophilic acylation by the low-temperature, in situ generation of acyllithium reagents a-hydroxy ketones from ketones 3-hydroxy-2,2,3-trimethyloctan-4-one from pinacolone. Org. Synth. 1993, Coll. Vol. VIII, 343-346. 

Seyferth, D. Weinstein, R. M. Hui, R. C. Wang, W.-L. Archer, C. M. Synthesis of a-hy-droxy ketones by direct, low-temperature, in situ nucleophilic acylation of aldehydes and ketones by acyllithium reagents./. Org. Chem. 1992, 57, 5620-5629. 

Cyclic selenoacetals 428 (R = H)641,642 can be lithiated with LDA and 4,6-dimethyl-1,3-diselenane 428 (R = Me)643 with n-BuLi at — 78 °C at the equatorial position. Axial functionalization has been achieved through a Se/Li exchange upon reacting 4,6-dimethyl-2-methylselanyl-l,3-diselenane with n-BuLi643. However, these 2-lithio-l,3-diselenanes have not been used as acyllithium reagents. 

Benzotriazol-l-yl)alkoxymethyllithiums 451 and 2-lithiooxazolidines 452 are two types of acyllithium reagents which can be considered as protected formyl anions with hemi-aminal structure. 

Acyllithium reagents, RCOLi, 11, 111. These unstable anions, when generated from RLi and CO at - 135° in the presence of a carbonyl compound (1 equiv.), can effect nucleophilic acylation to give acyloins. Since 1,2-addition of RLi is a competing reaction, acylation is favored when the carbonyl group is hindered and when R is secondary or tertiary. The anions also react with esters under the same conditions to give 1,2-diketones. ... 

Direct nucleophilic acylation of electrophiles (ketones, esters) by acyllithium reagents. 

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