sp2-Hybridized β-substituted organo-lithium, -sodium, and -potassium dianions; preparation, stability, and reactivity

Abstract

The reaction of the substituted 2-chloroallyl alcohol (3a) with ethylmagnesium bromide followed by lithium was found to give the β-substituted organolithium derivative (4) of the type CCC(Ō). Intermediates of this type were also prepared directly from (E)-2-chlorocrotonaldehyde (2) or 2-chloro-acrolein (19) by the same process using different Grignard reagents. The use of sodium or potassium as the metal in the second step of the process was found to give the corresponding organosodium or organopotassium derivative (24) or (25). A dilithiated dianion (26) was also obtained from the corresponding chlorohydrin (3d) by reaction with phenyl-lithium followed by lithium. These intermediates, which are stable species at room temperature, were found to react stereoselectively with electrophilic reagents leading to functionalized substituted allyl alcohols. The thermal stability of the lithiated dianion (4d) has also been investigated.