8. Reformatsky Reaction
This reactions is the condensation of a-halo esters with aldehydes or ketones in the presence of zinc to yield b-hydroxy esters.
The reaction involves the formation of a zinc enolate which is quite similar to Grignard reagent attacking nucleophilically on the aldehyde.
9. Simmons-Smith Reactions
Simmons-Smith reaction is a
stereospecific reaction of alkene with an organozinc carbenoid to form
cyclopropane rings. The reaction involves the insertion of a methylene group.
10. Riemer-Tiemann Reaction
The ortho
formylation of phenol is known as the Riemer-Tiemann reaction. The reaction
involves a carbene intermediate produced from chloroform in the presence of
NaOH, which then forms a C-C at the ortho position of the phenol.
11. Acyloin condensation
The reductive
coupling of esters in the presence of sodium metal gives an a-hydroxy ketone.
The reaction is known as acyloin condensation.
12. Arndt-Eistert Reaction
Arndt-Eistert reaction is the one
carbon homologation of carboxylic acids. The reaction involves three stepes. I.
conversion of carboxylic acid to acid chloride with thionyl chloride, II. Conversion
of acid chloride to diazoketone with diazomethane, and III. Conversion of
diazoketone to carboxylic acid which is one carbon higher than the starting
material.
13. Gattermann Reaction
Formylation of aromatic rings by
using HCN is the Gattermann reaction. A Lewis acid is used a catalyst leading
to the formation of a C-C bond.
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