2-(4-Meth­oxy­phen­yl)-4H-1,3,2-benzoxathia­phosphinine 2-sulfide

The asymmetric unit of the title compound, C14H13O2PS2, contains two crystallographically independent mol­ecules, which differ in the conformation of the 1,3,2-benzoxathia­phosphinine moieties (screw boat in the first mol­ecule and envelope in the second mol­ecule). In the crystal, neither classical nor non-classical hydrogen bonds are found. Weak inter­actions (about 2.9–3.0 Å) between the lone pair of the terminal S atoms with H atoms occur. This compound was further characterized by 1H NMR and IR spectroscopy

Three-Component Condensation of β-Ketonitriles, 4-Fluorobenzaldehyde, and Secondary Cyclic Amines

A new three-component condensation of β-ketonitriles, 4-fluorobenzaldehyde, and secondary cyclic amines was developed. A possible reaction mechanism has been proposed including Knoevenagel condensation followed by aromatic nucleophilic substitution. It was found that in the case of 3-oxopropanenitrile bearing the 6-amino-1,3-dimethyluracil moiety, the reaction is not accompanied by fluorine substitution in the Knoevenagel adduct, and the Michael addition of a secondary amine occurs followed by oxidation

Three-Component Condensation of β-Ketonitriles, 4-Fluorobenzaldehyde, and Secondary Cyclic Amines

A new three-component condensation of β-ketonitriles, 4-fluorobenzaldehyde, and secondary cyclic amines was developed. A possible reaction mechanism has been proposed including Knoevenagel condensation followed by aromatic nucleophilic substitution. It was found that in the case of 3-oxopropanenitrile bearing the 6-amino-1,3-dimethyluracil moiety, the reaction is not accompanied by fluorine substitution in the Knoevenagel adduct, and the Michael addition of a secondary amine occurs followed by oxidation

Reactions of <i>o</i>‑Quinone Methides with Pyridinium Methylides: A Diastereoselective Synthesis of 1,2-Dihydronaphtho[2,1‑<i>b</i>]furans and 2,3-Dihydrobenzofurans

A simple, general route to the 1,2-dihydronaphtho­[2,1-<i>b</i>]­furans and 2,3-dihydrobenzofurans substituted at C-2 by an acyl or aryl group, starting from phenolic Mannich bases and pyridinium ylides, has been developed. The mechanism of the reaction is believed to involve the formation of the <i>o</i>-quinone methide intermediate, Michael-type addition of the ylide to the <i>o</i>-quinone methide, followed by intramolecular nucleophilic substitution

Reaction of Push–Pull Enaminoketones and <i>in Situ</i> Generated <i>ortho</i>-Quinone Methides: Synthesis of 3‑Acyl‑4<i>H</i>‑chromenes and 2‑Acyl‑1<i>H</i>‑benzo[<i>f</i>]chromenes as Precursors for Hydroxybenzylated Heterocycles

A simple and efficient method for the synthesis of 4<i>H</i>-chromenes and 1<i>H</i>-benzo­[<i>f</i>]­chromenes containing a trifluoroacetyl or aroyl group in the pyran ring from <i>o</i>-quinone methide precursors and push–pull enaminoketones has been developed. The chromenes are presumably formed through an initial oxa-Diels–Alder reaction, followed by an elimination of amine. The possibility of further transformations of given chromenes to <i>o</i>-hydroxybenzylated pyrazoles, isoxazoles, and pyridines has been demonstrated

Divergent Transformations of 2‑Nitro‑1<i>H</i>‑benzo[<i>f</i>]chromenes in Reactions with Alkylidenemalononitriles: Access to Naphtho[2,1‑<i>b</i>]furans via Base-Mediated Pyran Ring Contraction

The action of 2-(1-arylethylidene)malononitriles on 2-nitro-1H-benzo[f]chromenes in the presence of Et3N and MoO3·2H2O results in naphtho[2,1-b]furans containing an allylidenemalononitrile unit in the α-position. The reaction proceeds with contraction of the pyran ring via a cascade carba-Michael addition/retro-oxa-Michael reaction/tautomerization/SN2/oxidation process. In contrast, the reaction of 2-nitro-1H-benzo[f]chromenes with the cyclic Knoevenagel adduct derived from 1-indanone and malononitrile leads to dihydroindeno[1,2-c]xanthenes. The possibility of further transformations of naphtho[2,1-b]furan derivatives as useful precursors and their optical properties were also investigated