Sequential Lactonization Research Articles

Synthesis of l-Ribose from d-Ribose by a Stereoconversion through Sequential Lactonization as the Key Transformation

l-Ribose, a key precursor of various l-nucleosides can only be synthesized from other sugars or other non-sugar precursors. Herein, the study involves the synthesis of naturally rare l-ribose from readily available d-ribose. Though, many synthetic strategies are developed to meet the increasing demands of l-ribose, seeking innovation, a synthesis employing sequential lactonization as the key transformation was explored. This novel conversion involves protection, oxidation, sequential lactonization, reduction with DIBAL-H, and deprotection.

Regioselective Intermolecular [2 + 2]-Cycloaddition of α-Iodo-Unsaturated Ketones Promoted by Diisobutylaluminum Hydride.

The development of intermolecular [2 + 2]-cycloaddition of α-iodo-unsaturated ketones in the presence of diisobutylaluminum hydride (Dibal-H) is reported to produce various trispirocyclic derivatives containing a cyclobutane ring. This sequential lactonization/[2 + 2]-cycloaddition proceeds in high regioselectivity under mild conditions.

Facile one-step synthesis of beta-alkoxy lactone via sequential lactonization and 1,4-addition of alkoxide group: total synthesis of all stereoisomers of dihydrokawain-5-ol.

We describe here a divergent total synthesis of all of the four stereoisomers of dihydrokawain-5-ol starting from alpha-D-glucose. The approach involves the use of Ando's modification of Horner-Wadsworth-Emmons homologation to give a alpha,beta-unsaturated ester. Subsequently, lactonization and 1,4-addition of OMe group in one step provided a delta-lactone, which was converted into the target compounds in two steps.