A [5 + 1] annulation strategy for the synthesis of multifunctional biaryls and p-teraryls from 1,6-Michael acceptor ketene dithioacetals

A [5 + 1] annulation approach was used to access multifunctional biaryls and p-teraryls from ketene dithioacetals.

Copper-catalyzed cascade cyclization reaction of 3-aminocyclobutenones with electron-deficient internal alkynes: synthesis of fully substituted indoles

A novel copper-catalyzed cascade cyclization reaction of 3-aminocyclobutenones with electron-deficient internal alkynes has been developed. This reaction provides a new method for the synthesis of fully substituted indoles by formation of four new bonds and two rings in a single step.

Oxidant-controlled divergent transformations of 3-aminoindazoles for the synthesis of pyrimido[1,2-b]-indazoles and aromatic nitrile-derived dithioacetals

An oxidant-controlled divergent reactivity of 3-aminoindazoles is presented, which enables the [3 + 3] annulation and C–H arylation of ketene dithioacetals in disparate pathways to assemble pyrimido[1,2-b]-indazoles and aromatic nitrile-derived dithioacetals.

Metal-Free Vinyl C-H Sulfenylation/Alkyl Thiolation of Ketene Dithioacetals for the Synthesis of Polythiolated Alkenes

The sulfenylation of the vinyl C-H bond in ketene dithioacetals leading to the synthesis of polythiolated alkenes is achieved via the promotion of molecular iodine. In addition, alkyl thiols also exhibit tolerance to the C-H bond elaboration reaction for the synthesis of corresponding alkylthiolated ketene dithioacetals.

Thermally induced formal [4+2] cycloaddition of 3-aminocyclobutenones with electron-deficient alkynes: facile and efficient synthesis of 4-pyridones

A thermally induced novel formal [4+2] cycloaddition of cyclobutenones with electron-deficient alkynes under metal-free conditions has been developed. The reaction provides a straightforward and efficient method for the synthesis of 4-pyridone derivatives in a single step.

Nickel-catalyzed ring-opening of α-hydroxycyclobutenones with a remarkable ligand effect

A Ni-catalyzed ring-opening of α-hydroxycyclobutenones is reported herein.

Cyclobutenones and Benzocyclobutenones: Versatile Synthons in Organic Synthesis

Cyclobutenones, four-membered ketones bearing an unsaturated carbon-carbon double bond, and their structural sibling benzocyclobutenones, possess unique reactivity. Owing to their inherent high ring strain, such structures readily undergo ring opening under a variety of conditions, including thermolysis, photolysis, and transition metal catalysis, to afford reactive intermediates that can be trapped with nucleophiles, dienophiles, and unsaturated bonds. Their electron-deficient enone moieties are good electrophiles for facile nucleophilic addition. Such properties render cyclobutenones versatile synthons, serving as excellent coupling partners in a vast array of synthetically valuable transformations.

A base-catalyzed cycloisomerization of 5-cyano-pentyne derivatives: an efficient synthesis of 3-cyano-4,5-dihydro-1H-pyrroles

A base-catalyzed cycloisomerization of 5-cyano-pentyne bearing a terminal alkyne group has been developed under metal-free conditions. This reaction provides an efficient access to 3-cyano-4,5-dihydro-1H-pyrroles with 1,3-cyano migration as the key transformation.

Recent developments of ketene dithioacetal chemistry

Ketene dithioacetals are versatile intermediates in organic synthesis. Extensive research, since the last decade, has given rise to new prospects in their chemistry. The objective of this review is twofold: first, to highlight the new prospects in the chemistry of functionalized ketene dithioacetals, and second, to provide an intrinsic link between ketene dithioacetal groups and a variety of other functional groups, which has brought out many new facts that will assist in future designs.

A straightforward synthesis of cyclobutenones via a tandem Michael addition/cyclization reaction of 2,3-allenoates with organozincs

An efficient method for synthesis of polysubstituted cyclobutenones, which are not readily available from traditional methods due to the intrinsic ring strain, is described. The reaction of 2,3-allenoates and organozinc reagents proceeds via a tandem Michael addition/cyclic 1,2-addition/elimination mechanism with the functional groups from the organozinc reagents being introduced to the 3-position of the cyclobutenone products regiospecifically in moderate to excellent yields. Application to the synthesis of stereodefined β,γ-unsaturated enones is demonstrated.