Progress in Heterocyclic Chemistry

A Critical Review of the 2000 Literature Preceded by Two Chapters on Current Heterocyclic Topics

G.W. Gribble, Thomas L. Gilchrist

• Publisher: Pergamon
• Year: 2001
• Print ISBN: 9780080440057
• eBook ISBN: 9780080539874
• Topic: Physical Sciences
• Subtopic: Organic Chemistry

This volume of Progress in Heterocyclic Chemistry(PHC) is the thirteenth annual review of the literature, covering the work published on important heterocyclic ring systems during 2000. In this volume there are two specialized reviews. The first, by H. Ila, H. Junjappa and P.K. Mohanta, covers their work on annulation using ?-oxoketene dithioacetals, a synthetic method that provides useful routes to an impressively wide range of fused heterocycles. The second, by R. N. Warrener, is on the synthesis of fused 7-azanorbornanes. The 7-azanorbornane structural unit is incorporated into a series of elegant polycyclic molecules with rigid geometry. The subsequent chapters, arranged by increasing heterocycle ring size, review recent advances in the field of heterocyclic chemistry with emphasis on synthesis and reactions.

Chapter 1

The Junjappa-Ila (JI)-Heteroaromatic Annulation: A New General α-Oxoketene Dithioacetals Mediated Inverse Method for the Synthesis of Benzo/Condensed Heterocycles and Related Heteroaromatization Processes

H. Ila, *[email protected]; H. Junjappa, *; P.K. Mohanta Department of Chemistry, Indian Institute of Technology, Kanpur-208 016, India, Fax: [phone]

1.1 INTRODUCTION

The classical methods for the synthesis of five and six membered benzoheterocycles generally involve a sequential construction of heterocyclic component over the preconstructed regiospecifically substituted benzene ring. This conventional benzoheterocyclic chemistry has been extensively investigated and still continues to be an active area of research. The required substitution pattern in the benzene ring of these heterocycles is generally achieved by subjecting the aromatic compounds to a series of stepwise electrophilic or nucleophilic substitution reactions. These efforts have evolved into elegant heteroaromatic chemistry from which a vast range of benzo-fused heterocycle compounds has emerged. However the synthesis of highly substituted benzene derivatives demands multistep reaction sequences which face difficulties of ortho, meta and para orientation resulting in the formation of isomeric mixtures and consequently poor yields of target molecules which negates the abundance of fossil resources. Some of these limitations are so prominently rigid that many of the substitution patterns still remain unexplored.

Modern methods for the synthesis of substituted aromatic compounds involve highly convergent annulation routes in which the aromatic system is assembled from acyclic precursors in a single step. Particularly noteworthy aromatic annulation reactions developed in recent years include methods based on Diels Alder chemistry, Robinson annelation <76S777> and transition metal mediated Fischer carbene complexes <91COS(5)1065>. However these annulation methods have found limited applications for benzoheterocycle synthesis i.e. construction of a benzene ring on to preconstructed heterocycles and the only transformations of potential general scope which fall under this category are [4 + 2] cycloaddition of heterocyclic o-quinodimethanes <99CRV3199> or benzoannulation with Fischer type heteroaryl carbene complexes.

Recently [3 + 3] benzoannulation reactions <99T8263> have become the subject of intense investigation primarily due to easy availability of three component synthons and high degree of regiocontrol observed in these reactions. Among many other variations of this category, [3 + 3] benzoannulation of α-oxoketene dithioacetals with allyl anions and its hetero variants developed in our laboratory (1984) have emerged as versatile general methods for the construction of...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright page
• Foreword
• Editorial Advisory Board
• Chapter 1: The Junjappa-Ila (JI)-Heteroaromatic Annulation: A New General α-Oxoketene Dithioacetals Mediated Inverse Method for the Synthesis of Benzo/Condensed Heterocycles and Related Heteroaromatization Processes
• Chapter 2: The Synthesis of Fused 7-Azanorbornanes
• Chapter 3: Three-Membered Ring Systems
• Chapter 4: Four-Membered Ring Systems
• Chapter 5.1: Five-Membered Ring Systems: Thiophenes & Se, Te Analogs
• Chapter 5.2: Five Membered Ring Systems: Pyrroles and Benzo Derivatives
• Chapter 5.3: Five-Membered Ring Systems Furans and Benzofurans
• Chapter 5.4: Five Membered Ring Systems: With More Than One N Atom
• Chapter 5.5: Five-Membered Ring Systems: With N & S (Se) Atoms
• Chapter 5.6: Five-Membered Ring Systems: With O & S (Se, Te) Atoms
• Chapter 5.7: Five-Membered Ring Systems: With O & N Atoms
• Chapter 6.1: Six-Membered Ring Systems: Pyridines and Benzo Derivatives
• Chapter 6.2: Six-Membered Ring Systems: Diazines and Benzo Derivatives
• Chapter 6.3: Six-Membered Ring Systems: Triazines, Tetrazines and Fused Ring Polyaza Systems
• Chapter 6.4: Six-Membered Ring Systems: With O and/or S Atoms
• Chapter 7: Seven-Membered Rings
• Chapter 8: Eight-Membered and Larger Rings
• Index