Stereoselective Synthesis of Hagen's Gland Lactones by Employing Vinylogous Mukaiyama Type Reaction

Abstract

Concise and stereoselective synthesis of Hagen's Gland Lactones is achieved by employing vinylogous Mukaiyama type reaction, Epimerization followed by oxy-Michael addition reaction to form bicyclic lactone as key steps with 54% overall yield. The synthetic route is economical and scalable within 5 steps without use of any toxic metals. The methodology could be useful for the synthesis of natural products containing bicyclic lactones and tetra substituted THF ring. Figure 3. Retrosynthetic analysis of Hagen's gland lactones. Scheme 1. Synthesis of Hagen's gland Lactones.

Graphene Oxide Catalyzed Synthesis of Fused Chromeno Spiro Pyrrolidine Oxindoles via Tandem Decarboxylation and 1,3-Dipolar Cycloaddition

“…Currently, the synthesis of complex molecules having appealing stereochemistry being synthesized by relatively simple protocol and environmental conscience is of utmost importance and can be largely correlated by frequent reports occurring in literature (Sharma et al, 2021;Singh et al, 2021). As a part of our group's research interest in sustainable and operationally simple, efficient sequences, we wish to report a simple and effective method mediated by azomethine ylide for the construction of a library of complex spiro-pyrrolizineindoline and spiro-pyrroleindoline molecules via 1,3-dipolar cycloaddition reaction in a one-pot, multicomponent approach using a heterogeneous catalyst (Chowhan et al, 2019;Lakshmi et al, 2020). Our synthetic approach started with 1,3-dipolar cycloaddition of α,β-unsaturated carbonyl compounds in equimolar concentrations, i.e., coumarin 3 and non-stabilized azomethine ylide, in situ generated via the condensation of isatin 1 and L-proline 2 in protic solvents (Scheme 1; Table 1).…”

Advances in Total Synthesis of Some 2,3,5‐Trisubstituted Tetrahydrofuran Natural Products

“…[13] Since then, there is one report on their synthesis recently. Chowhan and co-workers [100] in 2019 synthesized Hagen's Gland lactones using vinylogous Mukaiyama type reaction and intramolecular oxa-Michael addition as key steps (Scheme 38). The synthesis began with the aldehydes 249 a and 249 b, which on organocatalytic α-hydroxylation using L-proline and NaBH 4, reduction gave the diols 250 a (85%) and 250 b (86%), respectively.…”

Recent Advances in Total Synthesis of Bioactive Furo[3,2‐b]furanone Natural Products

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