A One-Pot Assembly of Fully Substituted Alkyl 5‑Aminothiophene-2-carboxylates from Allenes, Isothiocyanates, and Alkyl 2‑Bromoacetates

A novel simple approach to highly functionalized multisubstituted thiophenes such as alkyl 4-alkoxy-5-amino-3-methylthiophene-2-carboxylates through the one-pot sequential reaction of α-lithiated alkoxyallenes with isothiocyanates and alkyl 2-bromoacetates has been discovered. The process proceeds quickly (30–45 min) via in situ formation and intramolecular cyclization of alkyl 2-[(2-alkoxybuta-2,3-dienimidoyl)­sulfanyl]­acetates (1-aza-1,3,4-trienes)

Regioselective N(2)-H-functionalization of thiosemicarbazones of aromatic and heteroaromatic aldehydes with acrylonitrile

<p>Regioselective N(2)-H-cyanoethylation of thiosemicarbazones of aromatic and heteroaromatic aldehydes with acrylonitrile proceeds under mild conditions (14% KOH, acetone/H₂O, 35 °C, 6–21 h) to afford 1-(2-сyanoethyl)-2-[(<i>E</i>)-aryl(heteroaryl)methylidene]-1-hydrazinecarbothioamides in up to 74% yields. The synthesized thioamides are promising precursors of novel families of functionalized thiosemicarbazones as exemplified by hydrolysis of their cyano group to the corresponding amido function (46.5–60% yields).</p

Synthesis, Molecular Structure, Conformational Analysis, and Chemical Properties of Silicon-Containing Derivatives of Quinolizidine

A silicon analog of quinolizidine 3,3,7,7-tetramethylhexahydro-1<i>H</i>-[1,4,2]­oxazasilino­[4,5-<i>d</i>]­[1,4,2]­oxazasilin-9a-yl)­methanol <b>3</b> was synthesized. X-ray diffraction analysis confirmed the <i>trans</i> configuration and low temperature NMR spectroscopy both the flexibility (barrier of interconversion 5.8 kcal mol^–1) and the conformational equilibrium (chair–chair and chair–twist conformers) of the compound. The relative stability of the different isomers/conformers of <b>3</b> was calculated also at the MP2/6-311G­(d,p) level of theory. Intra- and intermolecular hydrogen bonding in <b>3</b> and the appropriate equilibrium between free and self-associated molecules was studied in solvents of different polarity. Both the N-methyl quaternary ammonium salt and the O-trimethylsilyl derivative of <b>3</b> could be obtained and their structure determined