A novel Lewis acid catalyzed intermolecular cascade annulation of alkynols with α-ketoesters has been developed. This simple and efficient cascade annulation proceeds through a 5-exo-dig cyclization of alkynols followed by annulation with α-ketoester to provide a wide variety of unsaturated γ-spiroketal-γ-lactones (1,6-dioxaspiro[4.4]non-3-en-2-ones) related to many natural products.

2-(Hetero)aryl tetrahydrofurans and tetrahydropyrans were successfully synthesized using Bi(OTf)3-catalyzed hydroalkoxylation (cycloisomerization) of alkynols (via 5 or 6 exo-dig cyclization) and intermolecular (hetero)arylation. This reaction involves a highly efficient cascade process, where initially the alkynol undergoes a cycloisomerization step via activation of the triple bond and generates the oxocarbenium ion, which subsequently participates in the (hetero)hydroarylation step with electron-rich arenes. Simple to complex suitably functionalized alkynols (4-pentyn-1-ols and 5-hexyn-1-ols) and electron-rich aromatic compounds were found to be reliable substrates in this cascade transformation and furnished a wide range of oxygen heterocycles. This practical tandem process provides a means to build libraries related to pharmacologically active molecules and natural product like scaffolds.

A full account of our efforts directed toward the stereoselective total synthesis of nannocystin A, a macrocyclic myxobacterial metabolite, is presented. In this endeavor, we have attempted two distinct synthetic routes to access polyketide fragment (C1‐C11) of macrocyclic depsipeptide (21‐membered) natural product from readily accessible building blocks 1,3‐propanediol and benzaldehyde employing Evans aldol, CBS reduction, Heck cross‐coupling, and Sharpless asymmetric epoxidation as key transformations. Ultimately, accomplished the synthesis of the complete skeleton (21‐membered precursor for macrocyclic depsipeptide) of the nannocystin A possessing desired stereochemistry and functional groups.