Temperature-Controlled Thiation of α-Cyano-β-Alkynyl Carbonyl Derivatives for De Novo Synthesis of 2-Aminothiophenes and Thieno[2,3-c]isothiazoles

Abstract

Making use of temperature-controlled thiation as a key operation, a simple route to 2-aminothiophenes or thieno­[2,3-c]­isothiazoles has been newly developed wherein the 2-aminothiophene nucleus was formed through an initial formation of thioamide followed by a 5-exo-dig addition to the tethered alkyne; however, under harsher thermal conditions, excess sulfur-transferring reagents enabled further oxidative thiation to generate the corresponding thieno­[2,3-c]­isothiazoles.

Organocatalytic Reductive Propargylation: Scope and Applications

“…Temperature has become a key factor in providing the reductive coupling 5ob–5qb products in good yields may be due to the less acidity of acyclic compounds 1o–q compared to cyclic 1,3-diones 1a–m (Table ). Based on the many applications of lawsone derivatives in medicinal to material chemistry, we performed three-component reductive coupling between lawsone 1d , 3-phenylpropiolaldehyde 2b , and Hantzsch ester 3 under the 4 -catalysis in DCM at 25 °C for 30 min to furnish the coupling product 5db in 98% yield (Table ). As lawsone 1d is a versatile synthon in organic reactions, we have also done a quick optimization on this particular coupling reaction of 1d , 2b , and 3 to find the correlation between the reaction rate/yield versus catalyst 4 loading, our observations are similar to cyclohexane-1,3-dione 1a (Table S1, see Supporting Information).…”

“…2-Benzoyl-5-phenylpent-4-ynenitrile (5ob). 6 The title compound was prepared following procedure A, purified by column chromatography using EtOAc/hexanes (0.5/9.5), and isolated as a pale yellow semi solid; yield: 80% (62. 23 mg).…”

“…13 SH,310.0902;found,. 6 The title compound was prepared following procedure A, purified by column chromatography using EtOAc/hexanes (0.2/9.8), and isolated as a pale yellow semi solid; yield: 75% (53.84 mg). IR (Neat): ν max 2970,2920,2850,2247,2189,1721,1661,1597,1475,1369,1065,907,757,729 and 690 cm −1 .…”

Diversity of Lawesson's Reagent: Advances and Scope

“…[28] Wu et al developed one pot two step procedure for the decoration of unique thieno [2,3-c]isothiazole 98 from the designed alkyne-appended nitrile 97. [29] During the course of the reaction extensive studies by changing the reaction conditions also revealed the isolation of 99 and 100. Predicted pathway manifested the involvement of cyclization step from 99 to furnish 100.…”

PdCl2/CuCl2/Bi(OTf)3‐promoted Construction of Sulfonyl Dibenzooxabicyclo[3.3.1]nonanes and Arylnaphthalenes via Intramolecular Annulation of Sulfonyl o‐Allylarylchromanones

“…Among these diverse kinds of reaction routes, a number of synthetic efforts have attempted to control one factor or variant to generate different products with approximate or distinct skeletons in recent reports. These adjusting factors included temperature, [1][2][3][4][5][6][7][8][9][10][11][12][13][14] catalyst, [15][16][17][18][19][20][21] additive (e. g. ligand, [22][23][24][25] base [26][27] and reagent [28][29][30][31] ) and solvent. [32][33][34][35] On the basis of the abovementioned investigations, we found that controlling the temperature change is a simple, economical and direct protocol for affecting the formation of different products in comparison with other variables.…”