Domino Knoevenagel hetero Diels-Alder reactions of sugar derived d,e-unsaturated aldehydes
John K. Gallos*and Alexandros E. Koumbis
Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, GR 54124, Greece
E-mail:
[email protected]
Dedicated to Professor Anastasios Varvoglis on the occasion of his 65th birthday
(received 01 Feb 03; accepted 25 Apr 03; published on the web 08 May 03)
Abstract
d,e-Unsaturated aldehydes prepared from D-glucose and D-ribose served as suitable substrates in intramolecular domino Knoevenagel hetero Diels-Alder reactions with N,N-dimethylbarbituric acid yielding polyhydroxylated carbocycle-dihydropyran fused ring systems.
Keywords: Domino Knoevenagel hetero Diels-Alder reaction, d,e-unsaturated aldehydes, carbocycles
Introduction
During the last decades a great number of domino (or tandem) reactions has been evolved.1 These versatile synthetic tools were wisely used for the synthesis of structurally diverse compounds along with biologically active natural products and drugs.2-4 One of the most fruitful categories, described as the domino Knoevenagel hetero Diels-Alder approach (DKHDA), involves a sequence of two in depth investigated and well recognized reactions.5-6 Tietze and his co-workers2-4,7-8 extensively studied and exploited this particularly simple way to construct fused heterocycles, usually in a stereoselective manner. Other groups also thoroughly employed this key sequence in their synthetic efforts.9-13 Prompted by our continuing interest in building carbocycles from carbohydrates14 we decided to explore the possibility of preparing novel carbocyclic derivatives through the intramolecular DKHDA approach following the retrosynthetic itinerary depicted in Scheme 1.
