27 research outputs found
Cyclopropanation of Various Substrates via Simmons-Smith and Michael-Initiated Ring Closure (MIRC) Reactions
Cyclopropanation of various electron rich and electron deficient olefins via Simmons-Smith and Michael-initiated ring closure reactions was studied in our research. Cinnamyl alcohol 18 was succesfully cyclopropanated in a good to excellent yield using Simmons-Smith reactions. Methyl and benzyl crotonate 14 and 16 were labile in MIRC reaction condition indicated by the detection of starting material degradation in the NMR spectra of the crude reactions, and allowed a low to moderate product yield. The other starting materials, i.e., cinnamaldehyde 19, methyl cinnamate 20, mono- and di-protected cross-coupled product (4R,5R,E)-methyl 5-(tert-butyldimethylsilyloxy)-4-hydroxyhepta-2,6-dienoate 25 and (4R,5R,E)-methyl 5-(tert-butyldimethylsilyloxy)-4-(methoxymethoxy)hepta-2,6-dienoate 26, were apparently incompatible to the reaction condition set in our study
Synthesis of Indenes by a BF<sub>3</sub>·OEt<sub>2</sub>‑Mediated, One-Pot Reaction of Aryl Homopropargyl Alcohols, Aldehydes, and Arenes
A new
and efficient protocol to prepare indenes is reported. Assisted
by boron trifluoride diethyl etherate, the one-pot reaction of aryl
homopropargyl alcohols and aldehydes in the presence of arenes yielded
indene derivatives. The reaction was studied with various substrates,
which suggests a cascade reaction including a sequence of Prins, Friedel–Crafts,
ring-opening reactions, and Friedel–Crafts to form three C–C
bonds leading to indenes
Anti-addition of Dimethylsulfoxonium Methylide to Acyclic α,β-Unsaturated Ketones and Its Application in Formal Synthesis of an Eicosanoid
Cyclopropanation using dimethylsulfoxonium
methylide (Corey–Chaykovsky
reaction) was examined with a series of linear α,β-unsaturated
ketones, and the results showed that the major trajectory for the
addition of the sulfur ylide to the enones is anti, related to the
γ-substituent. The stereochemical assignment for the generated
cyclopropanes was achieved by X-ray crystallography or comparing with
the reported spectroscopic data. We found that the diastereoselectivity
was influenced by several factors, including the protecting groups,
solvents, and temperatures, and good anti/syn ratios (>10:1) were
often obtained using the <i>tert</i>-butyldimethylsilyl
and <i>tert</i>-butyldiphenylsilyl-protected substrates.
The method was applied to a formal synthesis of a natural eicosanoid
with good efficiency
Microwave-Assisted Direct Thioesterification of Carboxylic Acids
A one-pot synthesis of thioesters
directly from carboxylic acids, <i>N,N</i>′-diphenylthiourea,
triethylamine, and primary
alkyl halides is described. Microwave-assisted heating and a catalytic
amount of 4-(dimethylamino)Âpyridine (DMAP) further improved the yields.
Both aromatic and aliphatic carboxylic acids were converted to the
corresponding thioesters, and many functional groups were compatible
with this reaction. Several possible reaction intermediates were investigated,
and the quaternary ammonium salts, derived from alkyl halides and
tertiary amines, were the intermediates to yield thioesters. A new
reaction mechanism for this thioesterification is proposed
Bortezomib Congeners Induce Apoptosis of Hepatocellular Carcinoma via CIP2A Inhibition
CIP2A is an oncoprotein that upregulates p-Akt and promotes cancer cell proliferation and survival. The proteasome inhibitor bortezomib has been shown to reduce CIP2A and lead to cell apoptosis. Here; we modified the functional group of bortezomib to generate a series of novel compounds and conducted a structure–activity relationship (SAR) study. The results showed that compound 1 was able to repress CIP2A expression and cell apoptosis in the same manner as bortezomib, but with less potency in inhibition of proteasome activity. This finding provides a new direction for the design of CIP2A inhibitors