Total Regio- and Diastereocontrol in the Aldol Reactions of Dienolborinates

Abstract

It is reported that appropriate dienolborinates can provide access to both diastereomers of 2-(hydroxymethyl)but-3-enoates through exclusive α-regiocontrol in a non-vinylogous pathway. Contrary to previous reports in which dialkylchloroboranes failed to enolize propanoates, acidity-enhanced but-3-enoates readily undergo enolization, offering unprecedented control over the formation of these valuable synthons. The first example of an aldol reaction in the presence of a phosphine-borane adduct is also reported.

Liquid Crystalline Benzoic Acid Ester MIDA Boronates: Synthesis and Mesomorphic Properties

“…Moisture-and/or oxygen-sensitive reactions were conducted using common Schlenk techniques. The synthesis of MIDA, 48 4-(6-methyl-4,8-dioxo-1,3,6,2-dioxazaborocan-2-yl) benzoic acid, 40 trimethylphosphine, 49,50 and ethyl 3-butenoate 51 were performed according to literature procedures.…”

Alkanethiolate-Capped Palladium Nanoparticles for Regio- and Stereoselective Hydrogenation of Allenes

“…Ethyl but-3-enolate was synthesized following the published procedure [29]. Briefly, pentane (5 mL) was placed in a 50 mL round bottle flask with ethanol (863 μL) and trimethylamine (1.34 mL) under 0 °C.…”

“…The organic solution was further dried by sodium sulfate before the removal of solvent using rotary evaporation. The purity and structure of the obtained product were confirmed according to the characterization data in the literature [29].…”

Enantio- and diastereoselective synthesis of syn -β-hydroxy-α-alkenyl carboxamides via reductive aldol reactions of morpholine 4-methyl-2,3-pentadienoic carboxamide with diisopinocampheylborane

“…[2][3][4] In contrast, highly diastereo-and enantioselective syntheses of the anti-diastereomers via aldol (and related) reactions are generally lacking. 5 We recently reported 6 a highly diastereoselective synthesis of syn-b-hydroxy-a-vinyl carboxylic esters 4 with good enantioselectivity via the reductive aldol reaction of allenyl ester 1 with 10-trimethylsilyl-9-borabicyclo[3.3.2]decane (2R, Soderquist's borane) (Fig. 1a).…”