Utilization of .alpha.,.beta.-unsaturated acids as Michael acceptors for the synthesis of thieno[2,3-b]thiopyrans

Highly Regioselective Synthesis of Oxindolyl-Pyrroles and Quinolines via a One-Pot, Sequential Meyer–Schuster Rearrangement, Anti-Michael Addition/C(sp3)–H Functionalization, and Azacyclization

“…In fact, the addition of nucleophiles to α,β-unsaturated systems in which strong electron-withdrawing substituents redirect the polarity of the double bonds at β-carbon is also a Michael addition concerning the strong electron-withdrawing group and double bond portion as the Michael acceptor. This concept has been explored under suitable conditions on systems with double bonds activated on both sides, and as a result, few synthetic studies and computational reports are available on anti-Michael addition. − …”

Additions of Organocopper Reagents and Heteroatom Nucleophiles to 1-Phenylseleno-2-(p-toluenesulfonyl)ethyne. Preparation of Vinyl and Allenic Sulfones and Formation of Michael, Anti-Michael, and Rearrangement Products

“…The predominantly anti-Michael regiochemistry in the additions of amines and alkoxides to 4 was unexpected, since conjugate additions of such nucleophiles to acetylenic sulfones are well known, 16a-h while those to acetylenic selenides are, to our knowledge, unprecedented. Some examples of anti-Michael additions to other types of acceptors have been previously reported and attributed to SET reactions, complexation effects, intramolecular additions, or the presence of electron-withdrawing β-substituents . Anti-Michael regioisomers have also been observed, among other products, in the additions of thiols to 2-arylalkynyl sulfones, particularly where the aryl group contained electron-withdrawing substituents 16k…”

New Synthesis of Thioflavanones by the Regioselective Cyclization of 1‐(2‐Benzylthio)phenyl‐3‐phenyl‐2‐propen‐1‐ones with Hydrobromic Acid

“…Several methods for synthesizing thioflavanones have been described through the construction of thiochroman‐4‐one ring as a key step . The reaction of thiophenols and cinnamic acids afforded 3‐(phenylthio)‐3‐phenylpropanoic acids, which were converted to the corresponding acid chlorides with oxalyl chloride, followed by cyclization with SnCl 4 to give the thioflavanones (Scheme (a)) . The treatment of 2′‐halochalcones, which were prepared from 1‐(2‐halophenyl)ethanones and benzaldehydes using NaOH, with NaSH or potassium ethyl xanthogenate/10 mol % Cu(OAc) 2 produced the corresponding 3‐phenyl‐1‐(2‐sulfanylphenyl)propenones in situ , followed by intramolecular 1,4‐addition to afford the thioflavanones under heating conditions (Scheme (b)).…”