Tetrahedron report number 195 (R)- and (S)-2,3-0-isopropylideneglyceraldehyde in stereoselective organic synthesis

2,2′-Bipyridine Lariat Calixcrowns: A New Class of Encapsulating Ligands Forming Highly Luminescent Eu3+ and Tb3+ Complexes

“…This approach also seemed particularly attractive to us because of the possibility of direct access to one of the two enantiomers of compound 11, which can be easily prepared from the wellknown and useful chiral synthon (R)-or (S)-2,3-O-isopropylideneglyceraldehyde. [17] Ditosylates 15 and 16 of 2-allyloxymethyl tri-and tetraethylene glycols were prepared through the reaction sequence depicted in Scheme 1. First, 1-O-allyl-glycerol [(dl)-11] was protected on the primary hydroxyl by reaction with trityl chloride and triethyl amine in dichloromethane.…”

Glicerol: um breve histórico e aplicação em sínteses estereosseletivas

“…O trabalho possibilitou a preparação de um novo equivalente sintético (21) do gliceraldeído acetonídeo (2), o qual é um bloco de construção quiral importante em síntese orgânica. 34 A reação de 32 com glicerol, na presença do catalisador ácido canforssulfônico (CSA) em ebulição com tolueno, resulta numa completa diastereosseletividade, para dar o dispirocetal 33. A configuração absoluta de 33 pôde ser determinada por dados espectrais de RMN de seu éster de Mosher correspondente.…”

A New Synthetic Method for the Preparation of α,β‐Didehydroamino Acid Derivatives by Means of a Wittig‐Type Reaction. Syntheses of (2S,4S)‐ and (2R,4R)‐4‐Hydroxyprolines.

“…The residual oil was subjected to preparative TLC (SiO 2 , hexane:ethyl acetate = 10:1, v/v) to afford pyrrole compound 24 in 52% yield (a pale-yellow oil, 65 mg). IR (neat) 2980, 2931, 1751, 1726, 1449, 1419, 1394, 1370, 1349, 1318, 1269,1213, 1194, 1159, 1094, 1064, 849, 775, 744, 705 cm −1 ; 1 H NMR (300 MHz; CDCl 3 ) δ 1.35 (t, J = 7.2 Hz, 3H), 1.58 (s, 9H), 4.23 (q, J = 7.2 Hz, 2H), 6.16 ( dd,J = 1.7,3.3 Hz,1H),6.83 (dd, J = 1.5, 3.3 Hz, 1H), 7.31 (dd, J = 1.7, 2.8 Hz, 1H); EI-MS m/z 239 (M + ; 6.6%). Ethyl (4S)-N-Boc-4-t-butyldiphenylsiloxy-α α α α,β β β β-didehydroprolinate (25a): To a solution of Ph 3 P (787 mg, 3.00 mmol) in CH 2 Cl 2 (15 mL) was added DEAD (323 mg, 3.04 mmol, 40% toluene solution) at 0 ° C under a N 2 atmosphere.…”

“…With ( R )-isopropylideneglyceraldehyde, 6 compound 12a with predominantly the ( Z )-configuration ( Z / E = 95/5 ) was obtained in 94% yield (Entry 12). In the same way, a variety of α , β -didehydroamino acid derivatives 2b -11b were successfully synthesized by the reaction of 1b and various aldehydes in good yields, respectively (except for Entry 19).…”