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In organic chemistry, methylenation is the transfer of a methylene group [= CH 2 ] from one molecule to another within a chemical reaction ( donor-acceptor principle ). The methylenation is thus an alkene synthesis.

Takai-Lombardo reaction for the methylenation of a sterically hindered ketone.

For example, the Lombardo reagent - produced in situ from titanium (IV) chloride , elemental zinc and dibromomethane in THF - is used as methylenation reagents for ketones in the Takai-Lombardo reaction . Similarly, the Wittig reaction with the Wittig reagent Ph 3 P = CH 2 allows the methylenation of aldehydes and ketones .

See also

Individual evidence

  1. Joachim Buddrus: Fundamentals of Organic Chemistry , 4th edition, de Gruyter Verlag, Berlin, 2011, p. 499, ISBN 978-3-11-024894-4 .
  2. ^ Siegfried Hauptmann : Organic Chemistry , 2nd revised edition, VEB Deutscher Verlag für Grundstoffindindustrie, Leipzig, 1985, p. 540, ISBN 3-342-00280-8 .