Rieke zinc as a reducing agent for common organic functional groups

Synthesis of novel polyhydroxylated pyrrolidine–triazole/-isoxazole hybrid molecules

“…10 Cleavage of the N-O bond of 2 using Zn/AcOH conditions gave vinyl pyrrolidine 5 instead of the desired alkynyl pyrrolidine 6 (Scheme 2). 11 These problems required our synthetic strategy to be redesigned (Scheme 3). Fortunately, the TMS-masked acetylene moiety in 7 was found to withstand the Zn/AcOH reductive conditions 12 and the key alkyne 8 was successfully obtained in 81% yield from 7 over three steps.…”

“…Attempts to react 8 with 4-methylbenzaldehyde oxime and bleach 14 under biphasic conditions were unsatisfactory due to the poor yield (<30%). In contrast, treatment of 8 with N-hydroxy-4-methylbenzimidoyl chloride (11), prepared by the treatment of 4-methylbenzaldehyde oxime with N-chlorosuccinimide (NCS) under basic homogeneous conditions, 15 afforded 12 in good yield (70%) as a single adduct with excellent regioselectivity. After global deprotection of 12 by treatment with BCl 3 in CH 2 Cl 2 at −78 °C, 16 the C-2-isoxazolyl polyhydroxylated pyrrolidine 13 was obtained in 73% yield.…”

“…[α] 20 D +11.90 (c 0.13 in MeOH); IR (neat): 3313 (br), 2955 (m), 2924 (s), 1612 (m), 1403 (s) cm -1 ; 1 H NMR (600 MHz, CD 3 OD) δ 2.39 (s, 3 H), 3. 1H),3.66 (dd,J = 5.2,11.2 Hz,1H),3.70 (dd,J = 4.5,11.2 Hz, 1H), 4.01 (t, J = 5.0 Hz, 1H), 4.16 (t, J = 5.8 Hz, 1H), 4.34 (d, J = 6.5 Hz, 1H), 6.82 (s, 1H), 7.28 (d, J = 8.1 Hz, 1H), 7.70 (d, J = 8.1 Hz, 1H); 13 C (150 MHz, CD 3 OD) δ 174. 7, 163.9, 141.8, 130.8, 127.9, 127.5, 101.1, 77.3, 73.7, 66.6, 63.7, 60.6, 21.5 (2R,3R,4R,5R)-tert-Butyl 3,4-bis(benzyloxy)-5-((benzyloxy)methyl)-2-((hydroxyimino)methyl)pyrrolidine-1-carboxylate (16).…”

Remarkable Effect of Bases on Core–Shell AgNP@CeO2 Nanocomposite-catalyzed Highly Chemoselective Reduction of Unsaturated Aldehydes

“…1 In this context, the chemoselective reduction of unsaturated carbonyl compounds while maintaining the reducible C=C bonds is an important and challenging objective, because the corresponding unsaturated alcohols often serve as valuable intermediates for fragrances, pharmaceuticals, agrichemicals, and resins. 2 Chemoselective reduction has been performed by using stoichiometric reagents such as metal borohydrides, 3 diisobutylaluminum hydride, 4 and zinc metal, 5 which produce large amounts of waste. For the replacement of such traditional stoichiometric reactions, much effort has been devoted to the development of catalytic systems.…”

Retracted article: Cross coupling in water: Suzuki–Miyaura vinylation and difluorovinylation of arylboronic acids

“…30 Vinylferrocenes are important precursors for polymers with variable electronic properties; 31,32 the protocol reported here provides a simple one step synthesis.…”