Organolithiums reaction with carbonyl compounds

Heterosubstituted allenes are versatile synthetic intermediates. Direct substitution of a heteroatom on the allene confers upon the system an electronic bias that allows the molecule to be deprotonated easily using an organolithium reagent, and also permits regioselective reaction with carbonyl compounds. 

Sulphoximine ylides also have been prepared using organolithium reagents as the base, but the presence of the lithium cation changes the course of the reaction with carbonyl compounds and with conjugated... 

The reactions of organolithium compounds with carbonyl compounds, including carbon dioxide, may be interpreted as follows ... 

The competition between insertion and hydrogen transfer is also crucial to the selectivity of the reaction of aluminium alkyls with carbonyl compounds. Aluminium alkyls, like organolithium compounds and Grignard reagents, can add to aldehydes and ketones to form secondary or tertiary alcohols, respectively. If the aluminium alkyl has a j -hydrogen, however, reduction of the carbonyl compound is a common side reaction, and can even become the main reaction [16]. Most authors seem to accept that reduction involves direct j5-hydrogen transfer to ketone. 

Similarities and Differences in the Reactions of Organolithium vs. Grignard Reagents with Carbonyl Compounds... 

In a synthetic effort directed toward a segment of erythronolide A, the addition of (2) to aldehyde (22) gave, after treatment with MeMgBr/CuI, an approximately 80 20 mixture of ring-opened products (23) and (24 equation ll). Interestingly, direct alkylation of this aldehyde (as a mixture of double bond isomers) with ethyllithium gave an 18 82 mixture of adducts. The factors responsible for the complementary face selectivity shown by (2) versus ethyllithium are unclear. Comparisons are particularly difficult due to the fact that most organolithium additions to carbonyl compounds are irreversible, kinetically controlled processes, whereas reactions of (2) can be reversible. 

T.3.3 Correlate reaction the reaction of telluronium salts with carbonyl compounds mediated by organolithium reagents - formation of secondary alcohols... 

In the case of 2,3-benzofuran (55), a stereoselective ring opening lithiation takes place under the same reaction conditions as for 2,3-dihydrobenzofuran (47) shown in Scheme 13, yielding the (Z)-organolithium intermediate (56) which, by reaction with different electrophiles and final acidic hydrolysis, gives the expected (Z)-products (57). The cyclization of the products obtained by reaction of intermediate (56) with carbonyl compounds under acidic conditions, affords the expected substituted 2H-chromenes (58) (Scheme 15) (01EJ02809). 

USE OF CERIUM(III) CHLORIDE IN THE REACTIONS OF CARBONYL COMPOUNDS WITH ORGANOLITHIUMS OR GRIGNARD REAGENTS FOR THE SUPPRESSION OF ABNORMAL REACTIONS ... 

Reagents of the type (1) can be prepared by the reaction of triphenylvinyl-silane with organolithium compounds. They react with carbonyl compounds to... 

---