Ene reactions of 2-borylated α-methylstyrenes: a practical route to 4-methylenechromanes and derivatives

Abstract

4-Methylenechromanes were prepared via a three-step process from 2-borylated α-methylstyrenes using a glyoxylate-ene reaction catalyzed by scandium(iii) triflate and Mitsunobu cyclization as key steps.

A Convenient, Rapid, Conventional Heating Route to MIDA Boronates

“…Indeed, the samples that were subjected to our new were rather broad in scope, encompassing boronic acids based on an aryl 1, isox MIDA boronates occupy a central role in organic synthesis with many applications including, but not limited to, masked boronic acids in total synthesis [8][9][10]; catalysis [11][12][13][14][15][16][17], including iterative or telescopic couplings [17][18][19][20][21]; oxidation chemistry [22] or as C1 or C2 building blocks [23,24]. Although traditionally made by a Dean-Stark protocol, usually employing DMSO as solvent [25][26][27][28], many recent methods have shifted towards milder reaction conditions, more convenient work-up, purification and isolation techniques, notably to enable the synthesis of unstable esters such as 2-phenol [12] or 2-hetero-aryl MIDA analogues [29]. We wish now to disclose a conventional, sealed, heating reactor-based synthesis of MIDA boronates that offers a cheaper, effective alternative to our earlier disclosed microwave-mediated route [30].…”

Ortho/Ipso Alkylborylation of Aryl Iodides

“…Additionally, boronic ester 25 was elaborated to several different derivatives that have no prior route for preparation. For example, under oxidative conditions, boronic ester 25 was converted to naphthol 41 . Copper mediated azidation and chlorination of 25 were also accomplished in 92% and 96% yield to give 42 and 44 , respectively .…”