Zilong Tang

Synthesis of Piperidine Derivatives by Reduction of Pyridinium Salts

Abstract Piperidine derivatives 1a–e and 2a–f have been prepared by the reduction of 3‐and 4‐substituted pyridinium salts with NaBH4 in moderate to excellent yields. The reactions regioselectively give 1,2,5,6‐tetrahydropyridines, and the yields depend greatly upon the nature of substituents on the phenyl ring and on the nitrogen atom, the nature and the position of the substituents on the pyridyl ring, and the chain length between the aryloxy and the pyridyl groups.

CuI-catalyzed domino reactions for the synthesis of benzoxazine-fused isoquinolines under microwave irradiation

ABSTRACT A small library of benzoxazine-fused isoquinolines has been synthesized under microwave irradiation (MW) via CuI-catalyzed domino reactions of o-alkynyl aldehydes and amines having embedded nucleophiles. This strategy offers a operationally simple, environmentally acceptable route to synthesize benzoxazine-fused isoquinolines in moderate to good yields. All new compounds were characterized by 1H NMR, 13C NMR, infrared, and high-resolution mass spectrometry techniques. GRAPHICAL ABSTRACT

SnCl4-Catalyzed Aza-Acetalization of Aromatic Aldehydes: Synthesis of Aryl Substituted 3,4-Dihydro-2H-1,3-benzoxazines

Abstract Stannic tetrachloride was an efficient Lewis acid catalyst for the aza-acetalization of aromatic aldehydes with o-arylaminomethyl phenols, and a series of novel aryl substituted 3,4-dihydro-2H-1,3-benzoxazines were prepared in good yields under mild conditions. SnCl4 was a more efficient catalyst for the reaction than p-toluenesulfonic acid, sulfuric acid, and aluminium chloride. GRAPHICAL ABSTRACT

Synthesis of Novel (p‐Substituted Styryl) Spirobenzopyrans

Abstract A series of (p‐substituted styryl) spirobenzopyrans were synthesized by the Wittig reaction of Fishers bases with 5‐(p‐substituted styryl) salicylaldehyde derivatives. The final spirobenzopyrans were characterized by the 1H NMR, IR, UV, and GC‐MS analyses.