Palladium(II) Acetate Catalyzed Stereoselective C-Glycosidation of Peracetylated Glycals with Arylboronic Acids

Abstract

[reaction: see text] Addition of a variety of arylboronic acids to peracetylated glycals takes place in the presence of a catalytic amount of Pd(OAc)(2). The reaction involves the syn addition of a sigma-aryl-Pd complex to the glycal double bond followed by anti elimination of Pd(OAc)(2) to provide a carbon-Ferrier type product. This method provides a practical and convenient stereoselective synthesis of C-arylglycosides.

Recent applications of the Suzuki–Miyaura cross-coupling reaction in organic synthesis

“…343,344 The resulting C-arylglycosides 397 and 399 acts as inhibitors of carbohydrate processing enzymes and can be used as building blocks for the synthesis of C-arylglycopyranosides and other natural products.…”

Di(isopropylprenyl)borane: A New Hydroboration Reagent for the Synthesis of Alkyl and Alkenyl Boronic Acids

“…The resulting solid residue was recrystallized from MeCN to give 4 a (3.34 g, 15.38 mmol, 77 % yield) as colorless needles. ; IR (KBr): ñ = 3000 (br), 1622,1598,1573,1494,1469,1454,1277,1242,1206 4,136.1,135.1 (br),128.4,126.5,125.7,62.5,50.4 ppm;MS (EI): m/z (%): 217 (M + , 1), 187 (9), 186 (100), 185 (8), 130 (7), 129 (9), 114 (87), 103 (25), 77 (15); elemental analysis calcd for C 12 H 16 BNO 2 : C 66.40,H 7.43,N 6.45;found: C 66.36,H 7.35,N 6.45.…”

“…[2,3] The significance of organoboron compounds in synthesis surged when Suzuki and Miyaura discovered the transition-metal-catalyzed cross-coupling reaction, [4] which more recently has seen explosive growth, particularly in industrial practice. [5] The current high activity in this area is evidenced by the further development of cross-coupling reactions of organoboron compounds for C À C [4][5][6] and C-heteroatom bond formation, [7] C-H insertion, [8] allylic substitution, [9] Diels-Alder and dipolar cycloaddition, [10] and 1,2-/1,4-addition processes. [11] Consequently, the quest for new reagents and procedures for the preparation of organoboronic acids and their derivatives is a continuing necessity.…”

The carbon-Ferrier rearrangement: an approach towards the synthesis of C-glycosides

“…The reagent system, developed by Maddaford et al, 28 produced the desired product with α-selectivity on the D-glycal substrates (Scheme 23). …”

“…with the α-anomer being the major product. 28 Thus, glucal 1 reacted with olefin 122 to give exclusively α-anomer the C-glycosylated 123 in 94% in the presence of SnBr 4 (Scheme 56). In the same way, glucal 59 gave 70% of only α-anomer 124.…”