•The mild acid-free one-pot reaction strategy for efficient synthesis of phenanthridines dyes.•A large scope of the substrates well used for this approach.•The chemical structures of the yielded phenanthridines well identified by various characterizations.•The roles of alcoholic solvents well demonstrated by the experiments.A series of new phenylphenanthridin dyes have been synthesized in the yields of 52–75% by a mild strategy in one-pot reaction. This is the first successful attempt to perform efficient soft acid-free reaction for phenanthridine ring construction. A large substrate scope was well demonstrated.

Electrophilic cyclization of 4-((3-arylprop-2-yn-1-yl)oxy)quinolin-2(1H)-one derivatives with iodine leads to the formation of 2H-pyrano[3,2-c]quinolin-5(6H)-ones bearing an alkenyl iodide moiety in good to excellent yields under mild conditions. The resulting iodo-containing 2H-pyrano[3,2-c]quinolin-5(6H)-ones could be further elaborated via palladium-catalyzed cross-coupling reactions.

A three-component reaction of triethoxysilanes, sulfur dioxide, and hydrazines catalyzed by copper(II) acetate is reported, leading to N-aminosulfonamides in good yields. Not only triethoxy(aryl)silanes but also triethoxy(alkyl)silanes are compatible during the process of insertion of sulfur dioxide. Additionally, diethoxydiarylsilanes are suitable under the conditions as well.

We describe two efficient protocols for the straightforward synthesis of 3H-pyrrolo[2,3-c]quinolin-4(5H)-one and thieno[2,3-c]quinolin-4(5H)-one derivatives from readily available 4-alkynyl-3-bromoquinolin-2(1H)-one as precursor. The efficient synthesis of highly functionalized 3H-pyrrolo[2,3-c]quinolin-4(5H)-ones has been achieved via a palladium-catalyzed domino reaction of 4-alkynyl-3-bromoquinolin-2(1H)-ones with amines. Thieno[2,3-c]quinolin-4(5H)-one derivatives were also conveniently synthesized via sequential nucleophilic aromatic substitution/5-endo-dig cyclization between 4-alkynyl-3-bromoquinolin-2(1H)-ones and sodium sulfide with good functional tolerance under mild conditions.

Biologically active 3H-pyrrolo[2,3-c]quinolin-4(5H)-ones have been synthesized in an efficient and concise manner utilizing readily available 4-hydroxyquinolin-2(1H)-ones as the starting material. The key strategy relies on the construction of the pyrrole ring through the palladium catalyzed sequential cross-coupling reaction and cyclization process.

A novel and unexpected reaction of 2-alkynylbenzaldoximes with ketenes in the presence of silver triflate (10 mol%) under mild conditions is discovered. This reaction proceeds through 6-endo-cyclization, [3 + 2] cycloaddition, and rearrangement, leading to isoquinoline derivatives in moderate to good yields.

A novel and unexpected reaction of 2-alkynylbenzaldoximes with ketenes in the presence of silver triflate (10 mol%) under mild conditions is discovered. This reaction proceeds through 6-endo-cyclization, [3 + 2] cycloaddition, and rearrangement, leading to isoquinoline derivatives in moderate to good yields.

Biologically active 3H-pyrrolo[2,3-c]quinolin-4(5H)-ones have been synthesized in an efficient and concise manner utilizing readily available 4-hydroxyquinolin-2(1H)-ones as the starting material. The key strategy relies on the construction of the pyrrole ring through the palladium catalyzed sequential cross-coupling reaction and cyclization process.