Enantioselective Photocyclization of N-Alkylfuran-2-carboxyanilides to trans-Dihydrofuran Derivatives in Inclusion Crystals with Optically Active Host Compounds Derived from Tartaric Acid

Abstract

The steric course of the photocyclization reaction of the title achiral compounds (1) to optically active trans-dihydrofuran derivatives (2) was controlled by carrying out the reaction in inclusion crystals (4) with optically active hosts (3) derived from tartaric acid. The mechanism of the enantioselective reaction of 1 in 4 was studied by X-ray structural analysis of 4. In some cases, the steric course of the photoreaction was different depending on whether 4 was prepared by recrystallization or by mixing of 1 and 3.

Palladium‐Based Catalytic System for the Direct C3‐Arylation of Furan‐2‐carboxamides and Thiophene‐2‐carboxamides

“…1 N-benzyl-2-furamide (26) [18] : Furan-2-carbonyl chloride (0.312 g, 2.4 mmol), benzylamine (0.214 g, 2 mmol), and triethylamine (4 mL) were stirred in CH 2 Cl 2 (30 mL) at RT for 3 h. The addition of a H 2 O/ HCl solution (100 mL), extraction with CH 2 Cl 2 , drying (MgSO 4 ), and purification by column chromatography on silica gel (pentane/diethyl ether 1:5) gave compound 26 in 75 % yield (0.302 g). 1 N-phenyl-2-furamide (27) [19] : Furan-2-carbonyl chloride (0.312 g, 2.4 mmol), aniline (0.186 g, 2 mmol), and triethylamine (4 mL) were stirred in CH 2 Cl 2 (30 mL) at RT for 3 h. The addition of a H 2 O/HCl solution (100 mL), extraction with CH 2 Cl 2 , drying (MgSO 4 ), and purification by column chromatography on silica gel (pentane/diethyl ether 1:9) gave compound 27 in 83 % yield (0.155 g). 1…”

Supramolecular Photochirogenesis

“…Relatively high ee ' s of 57% and 39% are attained respectively for 52 and 53 through optimization of the template/ guest ratio and the temperature. 55,108 Although similar reaction of furan -2 -carboxyanilide derivatives carried out in cocrystals with a chiral inductor give much better ee ' s, 109,110 the same photoreaction in solution never reaches such a level of enantioselectivity. 111 The Norrish -Yang cyclization of imidazolidinones 54 performed in the presence of chiral templates 44a -d 112,113 affords the endo and exo products 55 and 56 .…”

Palladium‐Catalyzed Direct Arylations of Five‐Membered Heteroarenes Bearing N‐Monoalkylcarboxamide Substituents

“…9, 158.6, 154.6, 148.2, 133.9, 130.7, 130.6, 124.6, 116.8, 109.7, 71.6, 59.4, 52.7, 39.4 N-Phenyl-2-furamide (27): [22] The reaction of furan-2-carbonyl chloride (0.312 g, 2.4 mmol) and aniline (0.186 g, 2 mmol) in triethylamine (4 mL) and dichloromethane (30 mL) at room temperature over 3 h gave 27 in 83 % (0.155 g) yield after addition of an H 2 O/ HCl solution, extraction with dichloromethane, drying (MgSO 4 ), and purification by silica gel column chromatography. (28): [20] 2- (Trifluoromethyl) Thiophene-2-carboxylic Acid Benzylamide (32): [23] The reaction of thiophene-2-carbonyl chloride (0.350 g, 2.4 mmol) and benzylamine (0.214 g, 2 mmol) in triethylamine (4 mL) and dichloromethane (30 mL) at room temperature over 3 h gave 32 in 74 % (0.…”