Alkenes bearing electron-withdrawing substituents are catalytically acetalized with 1,3-propanediol only by the use of PdCl2(MeCN)2 catalyst under O2 atmosphere. When a combination of BiCl3 and LiCl is used as co-catalyst, the acetalization proceeds effectively. These results indicate that a hydroperoxopalladium(II) species is most likely an active catalyst in the present reaction.
Treatment of terminal olefinsbearingelectron-withdrawing groups with (R,R)-pentane-2,4-diol (2) in the presence of PdCl2–CuCl–O2 in 1,2-dimethoxyethane gives cyclic acetals such as (3) and (12b)via attack at the terminal carbon atom; the corresponding acetals are similarly formed from propane-1,3-diol (5) and ethylene glycol (8).
Akguen, Eyuep; Pindur, Ulf, Liebigs Annalen der Chemie, 1985, # 12, p. 2472 - 2476
作者:Akguen, Eyuep、Pindur, Ulf
DOI:——
日期:——
Metal-free, PTSA catalyzed facile synthesis of β-ketoacetal from β-chlorocinnamaldehyde
作者:Avinash K. Srivastava、Munsaf Ali、Kamal Nayan Sharma、Raj K. Joshi
DOI:10.1016/j.tetlet.2018.07.022
日期:2018.8
A toluene solution of beta-chlorocinnamaldehyde and dihydroxy alcohols in the catalytic presence of paratoluenesulphonic acid (PTSA) yield the beta-ketoacetal in good to outstanding amount. The catalyst (PTSA), first selectively protect the aldehydic group to form the beta-chloroacetal and the subsequent dechlorination by H2O result the beta-ketoacetal. Significant transformation was achieved with electron donating substituent attached at the para-position of cinnamaldehyde. The selective formation of beta-keto-1,3-acetal was also obtained with a mixture of 1, 2- and 1, 3- diol. The present reaction consists of a metal-free, economical, robustly feasible, sizeable functional group tolerance and high yield properties. Moreover, the use of different dihydroxy alcohols made this process more benign and valuable towards the metal-free development of ketones. First, of its kind, a rare and unusual multitasking nature of PTSA is observed. (C) 2018 Elsevier Ltd. All rights reserved.