Divergent Reaction Pathways of β‐Chlorovinyl Ketones: Microwave‐Assisted Thermal Nazarov Cyclization versus Cycloisomerization via Soft Vinyl Enolization

Continuous Flow Synthesis of 1,4-Benzothiazines Using Ambivalent Reactivity of (E)-β-Chlorovinyl Ketones: A Point of Reaction Control Enabled by Flow Chemistry

A continuous flow system to 1,4-benzothiazines was developed using the point of reaction control, where the ambivalent (E)-β-chlorovinyl ketones and 2,2'-dithiodianilines were confined in a diffusion controlled flow setting. The successful segregation of reactive chemical species in a flow setting allowed more defined reaction pathways that are not feasible in traditional batch reaction conditions. The point of reaction control in flow systems helps to execute the reactions often plagued with the concurrent generation of multiple chemical species.

One-Pot Synthesis of N-Hydroxypyrroles via Soft α-Vinyl Enolization of (E)-β-Chlorovinyl Ketones: A Traceless Arylsulfinate Mediator Strategy

A traceless arylsulfinate mediator strategy has been developed to switch the reaction course of β-chlorovinyl ketones with N-hydroxyamine. The soft α-vinyl enolization of (E)-β-chlorovinyl ketones was conducted in the presence of sodium arylsulfinate to give transient alkenyl sulfones that in turn reacted with NH₂OH to give novel access to N-hydroxypyrroles. The mechanistic studies revealed the initial formation of oxazine intermediates that rearranged to thermodynamically stable aromatic products, N-hydroxypyrroles, under microwave-assisted heating conditions.

One-Pot Synthesis of (Z)-β-Halovinyl Ketones via the Cascade of Sonogashira Coupling and Hydrohalogenation

Herein, we report an efficient method for the synthesis of (Z)-β-halovinyl ketones through a one-pot Sonogashira coupling and hydrohalogenation reaction promoted by palladium-copper catalyst and Brønsted acid. The ynone intermediates are generated in situ from readily available acid chlorides and terminal alkynes at room temperature, which are directly converted to (Z)-β-halovinyl ketones by treating with triflic acid. This method avoids the use of an external halogen source and features broad substrate scope, high yield, and good to excellent stereoselectivity.