Synlett 2008(5): 629-644  
DOI: 10.1055/s-2008-1042807
ACCOUNT
© Georg Thieme Verlag Stuttgart · New York

On Inventing Catalytic Reactions via Ruthena- or Rhodacyclic Intermediates for Atom Economy

Teruyuki Kondo*
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
e-Mail: teruyuki@scl.kyoto-u.ac.jp;
Further Information

Publication History

Received 1 October 2007
Publication Date:
26 February 2008 (online)

Abstract

Novel catalytic reactions via ruthena- or rhodacyclic intermediates have been developed by our research group. We initiated our study from (1) ruthenium-catalyzed [2+2] cycloaddition of alkynes with alkenes, followed by developing (2) intramolecular Pauson-Khand-type reaction of 1,6-enynes, (3) hydroquinone synthesis, (4) cyclocotrimerization reactions, and (5) codimerization of styrenes with ethylene. Another approach to construct novel functional monomers, such as cyclopentenones, pyranopyrandiones, and substituted phenols, involves cleavage of carbon-carbon bonds in cyclobutenediones, cyclopropenones, and cyclobutenones. All reactions may proceed with high atom-efficiency via ruthena- or rhodacyclic intermediates, represented by ruthenacyclopentene, (maleoyl)ruthenium, and rhodacyclopentenone intermediates. In addition, rhodium-catalyzed [2+2+2] cocyclization of alkynes with isocyanates as well as novel ruthenium-catalyzed [2+2+1] cocyclization of alkynes, isocyanates, and carbon monoxide have been disclosed.

1 Introduction

2 Ruthenium-Catalyzed Cycloaddition of Alkynes with Alkenes

2.1 [2+2] Cycloaddition of Alkynes with 2-Norbornenes

2.2 Intramolecular Pauson-Khand-Type Reaction of Enynes with Carbon Monoxide

2.3 Cross-Carbonylation of Alkynes with 2-Norbornenes or Electron-Deficient Alkenes to Hydroquinones

2.4 Synthesis of Benzenepolycarboxylates by Cross-Benzannulation of Acetylenedicarboxylates with Allylic Compounds

2.5 [2+2+2] Cocyclization of Three Different Alkynes

2.6 Regio- and Stereoselective Dimerization of Styrenes and Linear Codimerization of Styrenes with Ethylene

3 Ruthenium- and Rhodium-Catalyzed Cleavage of C-C Bonds Leading to Reconstructive Synthesis of Novel Functional Monomers

3.1 Ru-Catalyzed Selective Monodecarbonylative Coupling of Cyclobutenediones with Alkenes to Cyclopentenones

3.2 Ru-Catalyzed Carbonylative Dimerization of Cyclopropenones and Cross-Carbonylation of Cyclopropenones with Alkynes to Pyranopyrandiones

3.3 Ru- and Rh-Catalyzed Ring-Opening Reactions of Cyclobutenones

3.4 Rh-Catalyzed Direct Synthesis of Substituted Phenols from Cyclobutenones and Electron-Deficient Alkenes

4 Ruthenium- and Rhodium-Catalyzed Cocyclization of Alkynes and Isocyanates

4.1 Rh-Catalyzed Cyclocotrimerization of Alkynes and Isocyanates to 2-Pyridones or Pyrimidine-2,4-diones

4.2 Ru-Catalyzed [2+2+1] Cocyclization of Alkynes, Isocyanates, and Carbon Monoxide

5 Summary

106

After the reaction, phenyl isocyanate (28a) still remained; however, longer reaction time did not improve neither the conversion of 28 nor the yield of 29. In the present reaction, decarbonylation of isocyanates occurred to some extent. The generated carbon monoxide may coordinate to an active rhodium species leading to deactivation of the rhodium catalyst, which accords well with the low catalytic activity of RhCl(CO)(PPh3)2