Rh-Catalyzed Conjugate Addition of Aryl and Alkenyl Boronic Acids to α-Methylene-β-lactones: Stereoselective Synthesis of trans-3,4-Disubstituted β-Lactones

Abstract

A one-step preparation of 3,4-disubstituted β-lactones through Rh-catalyzed conjugate addition of aryl or alkenyl boronic acids to α-methylene-β-lactones is described. The operationally simple, stereoselective transformation provides a broad range of β-lactones from individual α-methylene-β-lactone templates. This methodology allowed for a direct, final-step C-3 diversification of nocardiolactone, an antimicrobial natural product.

Indolylboronic Acids: Preparation and Applications

“…The reaction was performed in the presence of the ( R , R )-Phbod ligand, which ensured the 94% ee of the indole-based product (Table 11, entry 1). A ligandless condition was described by Howell et al (Table 11, entry 2) [191]. They studied the Michael addition of boronic acids onto α-methylene-β-lactones under similar reaction conditions [190].…”

Easily accessible non-aromatic heterocycles with handles: 4-bromo-2,3-dihydrofurans from 1,2-dibromohomoallylic alcohols

“…1A). [9][10][11] It occurred to us that the cyclization of 1,2-dibromohomoallylic alcohols 2 had the potential to provide either 4-bromo-2,3dihydrofurans 3 or 2-bromomethyleneoxetanes 4 (Fig. 1B).…”

Regioselective Carbonylation of 2,2-Disubstituted Epoxides: An Alternative Route to Ketone-Based Aldol Products

“…Because CO insertion typically occurs at the less-hindered carbon of the epoxide during carbonylation ( vide infra ), stereochemistry is retained. After carbonylation, these versatile β-lactone intermediates can be ring-opened, , providing a simple procedure for the generation of sought-after, enantioenriched ketone-aldol products (Scheme B).…”