Carbohydrate-Based Studies Toward the Synthesis of Hamigeromycin E: A Stereoselective Total Synthesis of an Isomer of Zeaenol

Chemoenzymatic asymmetric total synthesis of naturally occurring resorcylic acid lactones hamigeromycins F and G

Asymmetric total synthesis of two naturally occurring resorcylic acid lactones (RALs), hamigeromycins F and G, was achieved for the first time. The synthetic strategy involved a late-stage intramolecular macrolactonization achieved with a transesterification reaction. Stereocenters (C10' and C6') in both the molecules were accessed via an enzymatic kinetic resolution reaction. The penta-substituted aromatic core present in hamigeromycins F and G was accessed using vanillin as a precursor. The crucial E-olefinic unsaturated bond at C1'-C2' was constructed with a stereoselective Julia-Kocienski olefination reaction.

A facile construction of oxygen heterocycles by the reaction of benzoxepine-4-carboxylates with dihaloalkanes and activated alkynes

This manuscript describes the preparation of heterocyclic compounds such as naphtho[1,3]-dioxoles (3a-h), [1,4]-dioxines (4a-h), [1,4]-dioxepines (5a-c), [1,4]-dioxocines (6a-c) and diethyl 2-(2-ethoxy-2-oxoethyl)naphtho[1,3]dioxoles (8a-f). These heterocyclic compounds have been achieved by the reaction of benzoxepine-4-carboxylates (1a-h) with dihaloalkanes (2a-e) and activated alkyne (7a) for the first time. This work represents the first example for the construction of utile oxygen heterocycles by the formation of C-C and C-O bonds in a one step process.