Transition-metal-free Synthesis of tetra-substituted Vinyl Iodides by Cascade Sequential Reaction of α-Keto Acids, 1-Iodoalkynes, and Alkyl Halides

The cascade sequential reaction of α-keto acids, 1-iodoalkynes, and alkyl halides are reported herein to synthesize tetra-substituted vinyl iodides. It represents an efficient protocol to access a diverse range of tetra-substituted vinyl iodides starting from simple materials in a one-pot fashion, featuring mild reaction conditions, ease of operation, and broad substrate scope.

One-Pot Synthesis of α-Ketoamides from α-Keto Acids and Amines Using Ynamides as Coupling Reagents

A one-pot strategy for α-keto amide bond formation have been developed by using ynamides as coupling reagents under extremely mild reaction conditions. Diversely structural α-ketoamides were afforded in up to 98% yield for 36 examples. This reaction features advantages such as practical coupling procedure, wide functional group tolerance, and extremely mild conditions and has potential applications in synthetic and medicinal chemistry.

BF3·Et2O-Mediated annulation of α-keto acids with aliphatic ketones for the synthesis of γ-hydroxy-butenolides and γ-alkylidene-butenolides

Annulation reaction of α-keto acids with cyclic or acyclic aliphatic ketones is reported herein to divergently access γ-hydroxy-butenolides and γ-alkylidene-butenolides depending on the amount of BF₃·Et₂O. This protocol features good functional tolerance and ease of operation, to open a route to access butenolides via an annulation and dehydration process.

An efficient approach to divergently access γ-hydroxy-butenolides and γ-alkylidene-butenolides via annulation reaction of α-keto acids with simple aliphatic ketones is reported herein.

Difunctionalization of Alkynones by Base-Mediated Reaction with α,α-Dithioketones

A novel 1,2-difunctionalization of alkynones via an umpolung strategy for the synthesis of tetrasubstituted olefins has been developed. This procedure is realized by a formal C-C σ-bond cleavage reaction of cyclic α,α-dithioketones and subsequent deprotection. Notable features of this approach include excellent yields, mild reaction conditions, a broad substrate scope, and operational simplicity.

Synthesis of Spirolactones via a BF3·Et2O-Promoted Cascade Annulation of α-Keto Acids and 1,3-Enynes

A novel and effective method for the synthesis of spirolactones from readily available α-keto acids and 1,3-enynes is developed via a BF₃·Et₂O-promoted cascade annulation. This sequential process is conducted at room temperature, and it provides the functionalized spirolactones in good to excellent yield under metal-free conditions.

Photochemical synthesis of 3-hydroxyphenanthro[9,10-c]furan-1(3H)-ones from α-keto acids and alkynes

A novel and efficient method for the synthesis of 3-hydroxyphenanthro[9,10-c]furan-1(3H)-ones has been achieved from α-keto acids and alkynes through photo-initiated transformation, providing a range of products in good to excellent yields.

Visible-Light-Driven Alkyne Hydro-/Carbocarboxylation Using CO2 via Iridium/Cobalt Dual Catalysis for Divergent Heterocycle Synthesis

We present herein the first visible-light-driven hydrocarboxylation as well as carbocarboxylation of alkynes using CO₂ via an iridium/cobalt dual catalysis. Such transformations provide access to various pharmaceutically important heterocycles in a one-pot procedure from readily available alkynes. Coumarins, 2-quinolones, and 2-benzoxepinones were directly accessed through a one-pot alkyne hydrocarboxylation/alkene isomerization/cyclization sequence in which the Ir photocatalyst serves a dual role to promote single-electron transfer in alkyne hydrocarboxylation and energy transfer in the subsequent alkene isomerization. Moreover, an unprecedented cobalt carboxylation/acyl migration cascade enables alkyne difunctionalization to introduce γ-hydroxybutenolides with high efficiency. We expect that this cascade strategy will inspire new perspectives for alkyne and alkene difunctionalization.

A general two-step one-pot synthesis process of ynones from α-keto acids and 1-iodoalkynes

A two-step one-pot synthesis process of ynones was developed by cycloaddition of α-keto acids and 1-iodoalkynes followed by a ring-opening reaction.

Efficient synthesis of multiply substituted butenolides from keto acids and terminal alkynes promoted by combined acids

A general and efficient approach to highly substituted butenolides through the annulation of keto acids and terminal alkynes is described.