An odorless thia-Michael addition using Bunte salts as thiol surrogates
作者:Ya-mei Lin、Guo-ping Lu、Chun Cai、Wen-bin Yi
DOI:10.1039/c5ra01381j
日期:——
A newly developed C–S bond formation process via acid-catalyzed thia-Michael addition has been demonstrated. The protocol, in which Buntesalts generated from odorless and inexpensive sodium thiosulfate and organic halides are used as the thiol precursors, provides an efficient approach for the synthesis of β-sulfido carbonyl compounds.
Symmetrical disulfides (2a-m, 9, 13) were synthesized by oxidation or by a new reaction using ethyl α-bromomalonate from the corresponding thiazolidinecarboxylic acids containing a sulfhydryl group (1a-m, 8, 12). Mixed disulfides (14a-g) were synthesized by reaction of thiols (1a, c) with Bunte salt. Stereoselective acylation of the thiazolidinecarboxylic acid 5a gave the symmetrical disulfide 2c or the dicarboxylic acid 15, depending on the conditions. The absolute configurations of these disulfides were decided to be (2R, 2'R, 4R, 4'R) by comparison of nuclear magnetic resonance spectra and specific rotation with those of the (2S, 2'S, 4R, 4'R)-disulfide (4). The disulfides were tested for aldose reductase inhibitory activity in vitro. The symmetrical disulfide 2j and dicarboxylic acid 15 showed remarkably high potency.
Sodium 2-propenyl thiosulfate was identified in boiled garlic (Allium sativum). When canine erythrocytes were incubated with sodium 2-propenyl thiosulfate, the methemoglobin concentration and Heinz body percentage in erythrocytes were both increased, indicating that the compound induced oxidative damage in canine erythrocytes. It seems that this compound is one of the causative agents of garlic-induced hemolysis in dogs.
Doxorubicin (DOXO) is one of the most effective antineoplastic agents in clinical practice. Its use is limited by acute and chronic side effects, in particular by its cardiotoxicity and by the rapid development of resistance to it. As part of a program aimed at developing new DOXO derivatives endowed with reduced cardiotoxicity, and active against DOXO-resistant tumor cells, a series of H2S-releasing DOXOs (H2S-DOXOs) were obtained by combining DOXO with appropriate H2S donor substructures. The resulting compounds were studied on H9c2 cardiomyocytes and in DOXO-sensitive U-2OS osteosarcoma cells, as well as in related cell variants with increasing degrees of DOXO-resistance. Differently from DOXO, most of the products were not toxic at 5 mu M concentration on H9c2 cells. A few of them triggered high activity on the cancer cells. H2S-DOXOs 10 and 11 emerged as the most interesting members of the series. The capacity of 10 to impair Pgp transporter is also discussed.