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Cyclopropanization of Methyl Carboxylates with Tebbe-Type Reagents

✍ Scribed by Reza-Ali Fallahpour; Hans-Jürgen Hansen

Publisher
John Wiley and Sons
Year
1994
Tongue
German
Weight
349 KB
Volume
77
Category
Article
ISSN
0018-019X

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✦ Synopsis

Abstract

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.

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