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Cyclopropanization of Methyl Carboxylates with Tebbe ‐Type Reagents
Author(s) -
Fallahpour RezaAli,
Hansen HansJürgen
Publication year - 1994
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19940770817
Subject(s) - chemistry , reagent , ether , hydrolysis , medicinal chemistry , yield (engineering) , organic chemistry , metallurgy , materials science
The methylenation reaction of methyl azulene‐2‐carboxylates ( cf. Schemes 1 and 2 ) with Tebbe's or Takai's reagent is described. When the prescribed amount of Takai's reagent is applied in a four‐fold excess, the corresponding cyclopropyl methyl ethers are formed instead of the enol ethers ( cf. Schemes 2 and 3 ). Similarly, methyl benzoate and methyl 2‐naphthoate yield, after treatment with Takai's reagent and hydrolysis, the corresponding cyclopropanols 18 and 19 , respectively ( Scheme 3 ). The cyclopropyl methyl ether 4 or cyclopropanol 5 rearrange, on acid catalysis, into the l‐(azulen‐2‐yl)propan‐l‐one 20 ( Scheme 4 ). whose reduction with Et 3 SiH in CF 3 COOH yields the 2‐propylazulene 21 .