Electrophilic Cyanative Alkenylation of Arenes

Abstract

A variety of appropriately substituted internal alkynes were transformed into the corresponding cyano-substituted phenanthrenes, dihydronaphthalenes, and cyclohepta-1,3,5-trienes in moderate to excellent yields by treatment with imidazolium thiocyanate 1, which serves as an easy to handle [CN]+ precursor, in the presence of BCl3. The synthetic value of the method is additionally demonstrated by the transformation of the primarily obtained products into heavily substituted quinolines. Additionally, the dynamic properties of the prepared dibenzocyclohepta-1,3,5-trienes have been investigated.

Halogenation Reactions of Alkyl Alcohols Employing Methyl Grignard Reagents

“…TLC R f = 0.6 (5% EtOAc/hexanes, CAM stain); 1 H NMR (400 MHz, CDCl 3 ) δ 7.11 (ad, J = 8.6 Hz, 2H), 6.85 (ad, J = 8.7 Hz, 2H), 3.79 (s, 3H), 3.31 (at, J = 7.7 Hz, 2H), 3.11 (t, J = 7.8 Hz, 2H); 13 C­{ 1 H} NMR (150.9 MHz, CDCl 3 ) δ 158.5, 132.9, 129.4 (2C), 114.1 (2C), 55.3, 39.6, 6.4; IR (neat) 2954, 2833, 1611, 1510, 1463, 1301, 1245, 1176, 1122, 1034, 818, 754 cm –1 ; HRMS (TOF MS CI+) m / z : [M] + calcd for C 9 H 11 IO, 261.9855; found, 261.9842. Analytical data is consistent with literature values …”

“…; IR (neat) 2954, 2833, 1611, 1510, 1463, 1301, 1245, 1176, 1122, 1034, 818, 754 cm −1 ; HRMS (TOF MS CI +) m/z: [M] + calcd for C 9 H 11 IO, 261.9855; found, 261.9842. Analytical data is consistent with literature values 54. …”

Synthesis of Cycloheptatrienes, Oxepines, Thiepines, and Silepines: A Comparison between Brønsted Acid and Au‐Catalysis

“…Having identified the optimal catalyst and reaction conditions for the selective formation of cycloheptatrienes 12 , the scope and limitations of the Au‐catalyzed version of this transformation were explored . Provided that the ring suffering the electrophilic substitution is electron‐rich, the cyclization proceeds smoothly independently of the aliphatic or aromatic nature of the substituents at the alkyne.…”

“…All commercially available compounds (Acros Organics, ABCR, Alfa Aesar, Sigma Aldrich, Fluorochem, TCI, Chempur GmbH, J and K Scientific, Thermo Fisher Scientific) were used as received. Starting materials 4a‐l , 5a – 5l , 6a , 7a–b and Au catalyst C [ 15] were prepared according to literature known procedures or adaptation of those.…”

Synthesis of thiocyanato-containing phenanthrenes and dihydronaphthalenesviaLewis acid-activated tandem electrophilic thiocyanation/carbocyclization of alkynes

“…20 However, the electrophile-initiated carbocyclization of alkynes has proven to be a powerful tool for the formation of functionalized phenanthrenes. 21 To the best of our knowledge, the synthesis of 9-thiocyanatophenanthrenes, including the formation of both C(sp 2 )–SCN and C(sp 2 )–C(sp 2 ) bonds through a tandem reaction, has not been reported. On the basis of our continuing interest in electrophilic thiocyanation of alkynes, 22 we report herein the Lewis-acid-activated tandem electrophilic thiocyanation and cyclization of arene-alkynes using N -thiocyanato reagents (Scheme 1c, right).…”