Compounds bearing the isochroman ring system are found in natural and synthetic products of interest. The oxa-Pictet-Spengler condensation is a valuable tool for the preparation of polysubstituted isochromans and related oxygen-bearing heterocycles. The different stagings of the oxa-Pictet-Spengler reaction, as well as the scope and limitations of this transformation, are discussed.
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1 Introduction
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2 Intermolecular Oxa-Pictet-Spengler Condensation
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2.1 Synthesis of 1-Substituted Isochromans
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2.2 Synthesis of 1,1-Disubstituted Isochromans
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2.3 Diastereoselective Synthesis of 1,3-Disubstituted Isochromans
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2.4 Synthesis of 3-Substituted Isochromans
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2.5 Synthesis of C-4 Substituted Isochroman Derivatives
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3 Intramolecular Oxa-Pictet-Spengler Cyclizations
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3.1 Synthesis of 1-Substituted Isochromans
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3.2 Diastereoselective Synthesis of 1,3-Disubstituted Isochromans
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3.3 Synthesis of 1,3,4-Trisubstituted Isochromans
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4 The Oxa-Pictet-Spengler Condensation in the Absence of Acid Catalysts
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5 Naturally Occurring Oxa-Pictet-Spengler Cyclizations
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6 Oxa-Pictet-Spengler Reactions towards Optically Active Compounds
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7 Synthesis of Heterocycles other than Isochroman Derivatives
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8 Conclusions
oxa-Pictet-Spengler - cyclization - isochromans - natural products - chemical synthesis