A photocatalytic cascade cyclization of 1,7-enynes with acyl chlorides has been established. This method offers an operationally simple access to diverse fused pyran derivatives with a broad substrate scope in high yields from simple acyl chlorides via an acyl radical intermediate.
Herein we describe a mild method for the dual C(sp )-H bond functionalization of saturated nitrogen-containing heterocycles through a sequential visible-light photocatalyzed dehydrogenation/[2+2] cycloaddition procedure. As a complementary approach to the well-established use of iminium ion and α-amino radical intermediates, the elusive cyclic enamine intermediates were effectively generated by photoredox catalysis under mild conditions and efficiently captured by acetylene esters to form a wide array of bicyclic amino acid derivatives, thus enabling the simultaneous functionalization of two vicinal C(sp )-H bonds.
The intramolecular 1,5-H transfer reaction of the aryl radicals generated from unactivated aryl iodides by photocatalysis is described. The features of this transformation are operational simplicity, excellent yields, mild reaction conditions, and good functional group tolerance. With this approach, a more concise formal synthesis of (±)-coerulescine and (±)-physovenine is accomplished.
A powerful cascade reaction was developed for the synthesis of chromeno[4,3-b]pyrrolidines with high yields and excellent stereoselectivities. This efficient cascade reaction expeditiously established two fused rings which bear three contiguous stereogenic centers including one quaternary stereocenter in a single operation with low catalyst loading under mild conditions.
Herein, we report a general strategy for the rational design of an efficient organic photocatalyst, and we describe a robust method for the direct C(sp 3 )−H carbamoylation of saturated aza-heterocycles under mild conditions by using a naphthalimide (NI)-based organic photocatalyst. This protocol provides a concise and practical approach for the rapid installation of a valuable amide bond onto pharmaceutically useful saturated aza-heterocycles to access a wide range of cyclic α-amino amides. A series of mechanism investigations have demonstrated this transformation undergoes a visible-light photocatalytic, oxidative Ugi reaction process.
The first highly enantioselective α-fluorination of 2-acyl imidazoles utilizing iridium catalysis has been accomplished. This transformation features mild conditions and a remarkably broad substrate scope, providing an efficient and highly enantioselective approach to obtain a wide range of fluorine-containing 2-acyl imidazoles which are found in a variety of bioactive compounds and prodrugs. A large scale synthesis has also been tested to demonstrate the potential utility of this fluorination method.
Herein, we describe
a novel and efficient method for constructing
a series of fluorine-containing γ-keto acid derivatives through
combining visible-light photoredox catalysis and chiral Lewis acid
catalysis. With this dual catalytic strategy, a variety of chiral
γ-keto amides containing a gem-difluoroalkyl
group and a series of fluorine-containing α,β-unsaturated-γ-keto
esters were successfully constructed with high stereoselectivities,
respectively. A series of experiments showed that the chemoselectivity
of this process was highly dependent on the fluorine reagents besides
the Lewis acid catalysts. This approach facilitates rapid access to
γ-keto acid derivatives, an important class of precursors for
pharmaceuticals, plasticizers, and various other additives.
A method using aroyl chlorides as atom-transfer radical cyclization agents in a novel visible-light photocatalytic aroylchlorination reaction is developed. The overall transformation involves the formation of two new C−C bonds and one new C−Cl bond in a one-pot process. The advantages of this reaction include high atom/step/redox economy, mild conditions, operational simplicity, and broad substrate scopes.
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