Herein, we present a direct and efficient synthesis of diverse polysubstituted fused tetracyclic heterocycles with good functional group tolerance from diarylalkynes under different palladium catalytic systems. In this chemistry, an unprecedented intermolecular nucleopalladation of diarylalkynes through the highly selective sequential double insertion of isocyanide was achieved for the first time. The practicality of this method was further demonstrated by the construction of various bioactive molecules and important structural motifs, with potential applications in materials science and biochemistry. In addition, density functional theory calculations (DFT) elucidated an interesting “Pd walk” during the cyclization process.
An ew,r adical-mediated, divergentb icyclization of 1,n-enynes by a-C(sp 3 )-H oxidative functionalization of alkyl nitriles is described using the Sc(OTf) 3 andA g 2 Os ystem. Ther eactiona llowst he selectivef unctionalization of one or two C(sp 3 ) À H bonds a to the nitrile group by both oxidants and the substitution effect co-controlled the divergent bicy-clization reactions,a nd offersastep-and atom-economicala ccess to diverse polycycles with broad substrate scope and high selectivity.Scheme 2. Bicyclization of 1,n-enynes with alkyl nitriles. Reaction conditions: 1 (0.2 mmol), 2 (2 mL), Sc(OTf) 3 (10 mol%), Ag 2 O( 2equiv;0 .4 mmol), argon, 120 8 8Ca nd 24 h. The dr value is given in the parenthesis as determined by 1 HNMR analysis of the crude product.Scheme 3. Va riation of other enynes. Reaction conditions: 1 (0.2 mmol), 2 (2 mL), Sc(OTf) 3 (10 mol%), Ag 2 O (2 equiv., 0.4 mmol), argon, 120 8 8Cand 24 h.
Scheme4.Control experiments.Scheme5.Possible reaction mechanism.
The ability to selectively synthesize multiple products
from the
same sets of substrates is a highly appealing and challenging concept
in synthetic chemistry. In this manuscript, we describe the visible-light
photoredox intermolecular catalysis of N-arylacrylamides
that are α-C–H functionalized with aryl tertiary amines.
The photocatalyst acts as a chemical switch to trigger two different
reaction pathways and to obtain two different products from the same
starting material. Simple adjustments to the reaction conditions enable
the divergent synthesis of the oxidative cyclizations or the addition
products in good to high yields with excellent atom economy.
Herein, we present a direct and efficient synthesis of diverse polysubstituted fused tetracyclic heterocycles with good functional group tolerance from diarylalkynes under different palladium catalytic systems. In this chemistry, an unprecedented intermolecular nucleopalladation of diarylalkynes through the highly selective sequential double insertion of isocyanide was achieved for the first time. The practicality of this method was further demonstrated by the construction of various bioactive molecules and important structural motifs, with potential applications in materials science and biochemistry. In addition, density functional theory calculations (DFT) elucidated an interesting "Pd walk" during the cyclization process.
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