Carbolithiation tandem reactions

The addition of organolithiums to allylic alcohols followed by trapping of the intermediates by electrophiles is a good example of the usefulness of this type of carbolithiation. The sequence leads, generally, to the formation of diastereomeric alcohols, but the use of chiral ligands confers enantioselectivity to the tandem reaction. 

This volume, which complements the earlier one, contains 9 chapters written by experts from 7 countries. These include a chapter on the dynamic behavior of organolithium compounds, written by one of the pioneers in the field, and a specific chapter on the structure and dynamics of chiral lithium amides in particular. The use of such amides in asymmetric synthesis is covered in another chapter, and other synthetic aspects are covered in chapters on acyllithium derivatives, on the carbolithiation reaction and on organolithi-ums as synthetic intermediates for tandem reactions. Other topics include the chemistry of ketone dilithio compounds, the chemistry of lithium enolates and homoenolates, and polycyclic and fullerene lithium carbanions. 

Carbocyclization of m-alkcnyl-z-methoxybcnzy I lithiums to form five- or six-membered rings has been studied 101 the five-membered ring is formed with a cis-stereochemical relationship between the methoxy substituent and the adjacent methyl group. Intramolecular carbolithiation of vinyl sulfides at — 105°C in THF has been found to occur non-stereospecifically with regard to the newly formed C—Li centre.102. The stereochemistry of selective tandem Michael addition alkylation reactions of vinylphosphonates has been explored.103... 

The reaction of 1,4-dilithio-l,3-dienes with CO mentioned in Section n.A constitutes a useful methodology for the tandem synthesis of substituted 3-cyclopenten-l-ones with perfect trans selectivity (Scheme 5)105. Carbolithiation of unsaturated C—C bonds is a... 

Frequently seen are Parham cyclizations onto alkene side chains. For example, bromoalkene 39 undergoes cyclization and electrophilic trapping to afford 40. A series of allyl 2-lithioaryl ethers undergo a tandem Parham cyclization-y-elimination to afford 2-cyclopropylphenols, e.g., 41- 42. Intramolecular carbolithiation reactions of alkenes have led to 2-azabenzonorbomanes and tetrahydroisoquinolines. Similarly, carbolithia-tions of alkyne and allene side chains have been reported. Thus, both 43 and 45 undergo iodine-lithium exchange and cyclization to provide benzofuran 44 and fiiropyridine 46, respectively. 

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