Copper-Catalyzed Construction of Benzo[4,5]imidazo[2,1-a]isoquinolines Using Calcium Carbide as a Solid Alkyne Source

Diversely functionalized isoquinolines and their core-embedded heterocyclic frameworks: a privileged scaffold for medicinal chemistry

Isoquinoline-enrooted organic small-molecules represent a challenging molecular target in the organic synthesis arsenal attributed to their structural diversity and therapeutic importance. Into the bargain, isoquinolines are significant structural frameworks in modern medicinal chemistry and drug development. Consequently, synthetic organic and medicinal chemists have been intensely interested in efficient synthetic tactics for the sustainable construction of isoquinoline frameworks and their derivatives in enantiopure or racemic forms. This review accentuates an overview of the literature on the modern synthetic approaches exploited in synthesising isoquinolines and their core embedded heterocyclic skeletons from 2021 to 2022. In detail, the methodologies and inspected pharmacological studies for the array of diversely functionalized isoquinolines or their core-embedded heterocyclic/carbocyclic structures involving the introduction of substituents at C-1, C-3, and C-4 carbon and N-2 atom, bond constructions at the C1-N2 atom and C3-N2 atom, and structural scaffolding within isoquinoline compounds have been reviewed. This intensive study highlights the need for and relevance of relatively unexplored bioisosterism employing isoquinoline-based small-molecules in drug design.

1,2,4-Triazines and Calcium Carbide in the Catalyst-Free Synthesis of 2,3,6-Trisubstituted Pyridines and Their D-, 13 C-, and Doubly D2 -13 C2 -Labeled Analogues

A novel synthetic approach to 2,3,6-trisubstituted pyridines, their 4,5-dideuterated derivatives, 4,5-13 C2 - and doubly-labeled D2 -13 C2 -pyridines has been developed using catalyst-free [4+2] cycloaddition of 1,2,4-triazines and in situ generated acetylene or labeled acetylene. Calcium carbide and water or deuterium oxide were used for the in situ generation of acetylene and dideuteroacetylene. Calcium carbide-13 C2 in the mixture with water or deuterium oxide was applied as 13 C2 -acetylene and D2 -13 C2 -acetylene source.

One-Pot Synthesis of 1,2,3-Triarylindoles through Cascade Reactions Using Calcium Carbide, Iodoarenes, and Aromatic Amines

An efficient method for the construction of 1,2,3-triarylindoles through one-pot multicomponent reactions using calcium carbide, 3 mol of iodoarenes, and aromatic amines as starting materials was described. A series of target products were obtained by the simultaneous formation of five bonds in one step. The main advantages for this protocol are the use of a convenient alkyne source, wide scope of substrates, and simple workup procedure. The method can be extended to the gram scale.

Selective Monoethynylation of 2-Oxoacetamides Using Calcium Carbide as a Concise Solid Alkyne Source

An efficient selective monoethynylation of 2-oxoacetamides using calcium carbide as a concise solid alkyne source is described. A series of multifunctional compounds, 2-hydroxybut-3-ynamides, are synthesized by this strategy. The salient features of this protocol are the use of inexpensive and easy-to-handle solid alkyne source as a surrogate of inflammable and explosive gaseous acetylene, transition-metal-free and mild condition, wide scope of substrates, high selectivity, high yield, and simple work-up procedure.

Recent Advances in the Synthesis of Isoquinoline-Fused Benzimidazoles

This review includes recent developments in the synthesis of benzo[4,5]imidazo[2,1-a]isoquinolines with particular attention given to categorizing protocols based on the structural features of the ring architecture and crystallographically characterized reaction products.

One-Pot Synthesis of 3-Methyl-2-arylimidazo[1,2-a]pyridines Using Calcium Carbide as an Alkyne Source

An efficient method for the construction of 3-methyl-2-arylimidazo[1,2-a]pyridines from the reactions of calcium carbide, 2-aminopyridines, and aromatic aldehydes is described. The notable advantages for this strategy include the use of an inexpensive and concise solid alkyne source, cheap and readily available raw materials, wide-scope substrates, and a simple work-up procedure.