Synlett 2003(12): 1759-1777  
DOI: 10.1055/s-2003-41415
ACCOUNT
© Georg Thieme Verlag Stuttgart · New York

Introduction of Bicyclic Ketal Chemistry: Synthesis and Transformation Reaction of 6,8-Dioxabicyclo[3.2.1]octane Skeletal System

Jong-Gab Jun*
Department of Chemistry, Hallym University, Chunchon 200-702, South Korea
Fax: +82(33)2563421; e-Mail: jgjun@hallym.ac.kr;
Further Information

Publication History

Received 10 December 2002
Publication Date:
28 August 2003 (online)

Abstract

A stereo- and regioselective bicyclic ketal synthesis and several facile one-pot transformations of bicyclic ketals are described with plausible mechanisms. Products have included δ,ε-unsaturated ketones, mono- and diacetoxy ketones, transketalized ketones, cis- and trans-cyclic ethers, 1,5-diketones, cis-1,2-cyclopentanediols, 2,6-disubstituted pyridines, 2,3,6-trisubstituted pyri­dines, and conjugated and nonconjugated cyclohexenones.

1 Introduction

2 Synthesis of Bicyclic Ketal Structure

2.1 Stereoselective Introduction of C-7 Alkyl Group

2.2 Application to Natural Products Synthesis

2.3 Functionalization of Bicyclic Ketal Structure

2.3.1 C1 Alkylation

2.3.2 C4 Alkylation

2.3.3 C5 Alkylation

2.3.4 [3,3]-Sigmatropic Rearrangement of Dihydropyran Derivatives

3 Transformation Reactions of Bicyclic Ketal Structure

3.1 Selective C-O Bond Cleavage

3.1.1 Synthesis of Enone, Monoacetate, and Diacetate Derivatives

3.1.2 Synthesis of Cyclic Ethers

3.2 Rearrangement Reaction to 1,5-Diketones

3.2.1 Synthesis of 1,5-Diketones

3.2.2 Direct Synthesis of cis-1,2-Cyclopentanediols

3.2.3 Direct Synthesis of 2,6-Disubstituted Pyridines

3.2.4 Selective Enolization

3.3 Synthesis and Rearrangement Reactions of Ketal-Lactone Structure

4 Conclusion

47

Undesirable side products and non-homogeneous systems could be avoided by dilution with THF to 0.1-1.0 M, the anions were stable in THF once formed.