The Synthesis of Azulene Derivatives from Troponoids

Synthesis of 2- and 6-thienylazulenes by palladium-catalyzed direct arylation of 2- and 6-haloazulenes with thiophene derivatives

“…15 We have attempted the cross-coupling of 2 and 3 with thiophene derivatives 4-8 by using the catalytic system of 5 mol% Pd(OAc) 2 , 10 mol% PCy 3 ·HBF 4 and 30 mol% pivalic acid (PivOH) in the presence of K 2 CO 3 , which has been previously reported by Schipper and Fagnou. 15 We have attempted the cross-coupling of 2 and 3 with thiophene derivatives 4-8 by using the catalytic system of 5 mol% Pd(OAc) 2 , 10 mol% PCy 3 ·HBF 4 and 30 mol% pivalic acid (PivOH) in the presence of K 2 CO 3 , which has been previously reported by Schipper and Fagnou.…”

Hydroxylation and Amination of Azulenes by Vicarious Nucleophilic Substitution of Hydrogen

“…[1,4,14] The reported results indicate that VNS is a versatile tool for the introduction of a variety of oxygen, nitrogen, sulfur On the other hand we have found that 4-aminotriazole, proposed by Katritzky for the VNS amination of nitroar-and halogen substituents directly into azulene or by further conversion of hydroxyazulenes. enes, [11a] is an efficient aminating agent of azulenes when [18] and 1g by chlorination of azulene with Nchlorosuccinimide.…”

“…Ϫ Allylation of Hydroxyazulenes: The 6-hydroxyazulenes 2f or 2g HRMS (EI) m/z calcd. C 18 shaking the aqueous layer was separated, acidified with 10% HCl, (1 mmol) and the corresponding tetraalkylammonium salt extracted with ethyl acetate, the extract dried with MgSO 4 and the (2 mmol) in acetonitrile (10 mL) was refluxed for 4 hours (chlosolvent evaporated. The residue was chromatographed on silica gel ride), 6 hours (bromide) or 8 hours (iodide).…”

Unexpected Formation of 2‐Amino‐(1‐(2‐nitrophenylsulfinyl)azulene by the Reaction of 2‐Aminoazulene with 2‐Nitrobenzenesulfonyl Chloride

“…For example, in the case of the reaction of ethyl 2‐aminoazulene‐1‐carboxylate with isocyanates, 2‐ or 1‐substituted azulenes are yielded . In contrast, the amino group of 2‐aminoazulene allows for the easy production of an N ‐protected compound, 2‐acetamidoazulene, by acetylation . Generally, azulene derivatives having the amino group on a five‐membered ring are likely to decompose by oxidation or heating .…”