Formal [4+2] Cycloaddition of di-tert-Butyl 2-Ethoxycyclobutane-1,1-dicarboxylate with Ketones or Aldehydes and Tandem Lactonization

Ryohei Okado; Aya Nowaki; Jun-ichi Matsuo; Hiroyuki Ishibashi

doi:10.1248/cpb.60.21

Communication to the Editor

Formal [4+2] Cycloaddition of di-tert-Butyl 2-Ethoxycyclobutane-1,1-dicarboxylate with Ketones or Aldehydes and Tandem Lactonization

Ryohei Okado, Aya Nowaki, Jun-ichi Matsuo, Hiroyuki Ishibashi

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Keywords: donor-acceptor cyclobutane, [4+2] cycloaddition, tandem lactonization

JOURNAL FREE ACCESS

2012 Volume 60 Issue 1 Pages 21-22

DOI https://doi.org/10.1248/cpb.60.21

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Abstract

A catalytic amount of tin(IV) chloride catalyzed formal [4+2] cycloaddition reaction of di-tert-butyl 2-ethoxycyclobutane-1,1-carboxylate with ketones or aldehydes to give diethyl 6-ethoxydihydro-2H-pyran-3,3(4H)-dicarboxylates, whereas two equivalents of trimethylsilyl triflate promoted tandem [4+2] cycloaddition and lactonization to afford 3-oxo-2,6-dioxabicyclo[2.2.2]octane-4-carboxylate esters.

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