Asymmetric Catalytic Synthesis of Thiochromenes via an Acyl Transfer-Initiated Cascade
作者:Nicholas A. Ahlemeyer、Vladimir B. Birman
DOI:10.1021/acs.orglett.6b01639
日期:2016.7.15
A novel, reagent-free catalytic transformation of α,β-unsaturated thioesters into 2-substituted thiochromenes has been developed, with carbon dioxide as the only byproduct. Amidine-based catalysts, particularly homobenzotetramisole and its analogues, achieve high enantioselectivities and yields in this process.
Give it some stick: UV irradiation of spirothiopyran in an aqueous solution of goldnanoparticles (AuNPs) gives AuNP aggregates. The aggregate size is tuned by the photoirradiation time and the aggregation is facilitated by the covalent binding of photoisomerizedspirothiopyran to the surface of the AuNPs. This binding decreases the electrostatic repulsion between the AuNPs.
The biological importance of microtubules make them an interesting target for the synthesis of antitumor agents. The 2(3',4',5'-trimethoxybenzoyl)-5-aminobenzo[b]thiophene moiety was identified as a novel scaffold for the preparation of potent inhibitors of microtubule polymerization acting through the colchicine site of tubulin. The position of the methoxy group on the benzo[b]thiophene was important for maximal antiproliferative activity. Structure-activity relationship analysis established that the best activities were obtained with amino and methoxy groups placed at the C-5 and C-7 positions, respectively. Compounds 3c-e showed more potent inhibition of tubulin polymerization than combretastatin A-4 and strong binding to the colchicine site. These compounds also demonstrated substantial antiproliferative activity, with IC50 values ranging from 2.6 to 18 nM in a variety of cancer cell lines. Importantly, compound 3c (50 mg/kg), significantly inhibited the growth of the human osteosarcoma MNNG/HOS xenograft in nude mice.