Anti-Carboalumination of Alkynes Using Aluminum Trihalide and Silyl Ketene Imines: Stereo- and Regioselective Synthesis of Alkenylaluminum Compounds Bearing a Cyano Group

Copper-Catalyzed Regioselective Iodoformylation of Terminal Alkynes to Access Versatile Electrophiles (E)-β-Iodo-α,β-Unsaturated Aldehydes

Herein, we describe a method for synthesizing (E)-β-iodo-α,β-unsaturated aldehydes via the iodoformylation of terminal alkynes with TMSCF₃ and NaI. This synthetic method uses inexpensive and easy-to-handle chemical feedstocks and employs a commercially available CuI catalyst. It can transform a broad range of terminal alkynes into bis-electrophile (E)-β-iodo-α,β-unsaturated aldehydes with excellent chemoselectivity, regioselectivity, and stereoselectivity. Moreover, it was demonstrated that this protocol has abundant organic reactivity.

Copper-Catalyzed Cross-Coupling Between (E)-1,2-Diiodoethene and Carbazates: Entry to β-Functionalized N-Alkenylcarbazates

Aims:

This work aims to widen the scope of methodologies to prepare functionalized N-alkenylcarbazates.

Background:

Alkenylcarbazates are generally prepared via Aza-Baylis-Hillman reactions, nucleophilic attack on ketones or a tandem carbometallation/amidation reaction of alkynes.

Objective:

The objective of this work is to develop a method to prepare functionalized Nalkenylcarbazates that alleviates the problem encountered in the above methods (use of electron deficient alkenes, use of stoiechiometric amounts of metal, access to symmetrical dicarbazates only).

Methods:

Use of copper-catalyzed cross-coupling between vinylic diiodide and carbazates to prepare functionalized N-alkenylcarbazates.

Results:

Various β-iodovinylcarbazates were synthesized with up to good yields. The highest yields were obtained using dicarbazates. Functionalization of β-iodovinylcarbazate demonstrated that the vinyl iodide moiety of these molecules can be substituted by a variety of functional groups via transition metal-catalyzed coupling reactions.

Conclusion:

Copper-catalyzed cross-coupling reaction is efficient to prepare functionalized N-alkenylcarbazates.

Synthesis of (Z)-β-(Carbonylamino)alkenylindium through Regioselective anti-Carboindation of Ynamides and Its Transformation to Multisubstituted Enamides

The regioselective anti-carboindation of ynamides by using InBr₃ and silylated nucleophiles was developed to synthesize (Z)-β-(carbonylamino)alkenylindiums. The X-ray crystallographic analysis of an alkenylindium suggested that the reaction proceeded in an anti-addition fashion. In contrast to reported syn-carbometalations of ynamides by using organometallics, a cooperation of InBr₃ and silylated nucleophiles to ynamides achieved an anti-addition, which was supported by DFT calculations. The scope of substrates included various ynamides and silylated nucleophiles, such as silyl ketene acetals and silyl ketene imines. The transformation of synthesized alkenylindiums by iodination, radical coupling, and Pd-catalyzed cross-coupling successfully afforded trisubstituted enamines with high regio- and stereoselectivities.

Copper-catalyzed stereoselective alkylhydrazination of alkynes

An efficient copper-catalyzed stereoselective alkylhydrazination of alkynes, leading to tri-substituted (E)-alkenylhydrazines, has been developed.

Regio- and Stereoselective Allylindation of Alkynes Using InBr₃ and Allylic Silanes: Synthesis, Characterization, and Application of 1,4-Dienylindiums toward Skipped Dienes

Regioselective anti-allylindation of alkynes was achieved using InBr₃ and allylic silanes. Various types of alkynes and allylic silanes were applicable to the present allylindation. This sequential process used the generated 1,4-dienylindiums to establish novel synthetic methods for skipped dienes. The 1,4-dienylindiums were characterized by spectral analysis and treated with I₂ to stereoselectively give 1-iodo-1,4-dienes. The Pd-catalyzed cross coupling of 1,4-dienylindium with iodobenzene successfully proceeded in a one-pot manner to afford the corresponding 1-aryl-1,4-diene.