Selective Alkynylallylation of the C−C σ Bond of Cyclopropenes

• Published in: Angewandte Chemie 2021-01, Vol.133 (1), p.301-307
• Main Authors: Jiang, Zeqi, Niu, Sheng‐Li, Zeng, Qiang, Ouyang, Qin, Chen, Ying‐Chun, Xiao, Qing
• Format: Article
• Language: English
• Subjects: Allyl compounds; Chemical reactions; Chemistry; Cleavage; Couplings; Covalent bonds; cyclopropene; C−C bond cleavage; dicarbofunctionalization; Optimization; Organic compounds; Palladium; Reagents; Stereoselectivity; Substrates
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202008886

A Pd‐catalyzed regio‐ and stereoselective alkynylallylation of a specific C−C σ bond in cyclopropenes, using allyl propiolates as both allylation and alkynylation reagents, has been achieved for the first time. By merging selective C(sp2)‐C(sp3) bond scission with conjunctive cross‐couplings, this decarboxylative reorganization reaction features fascinating atom and step economy and provides an efficient approach to highly functionalized dienynes from readily available substrates. Without further optimization, gram‐scale products can be easily obtained by such a simple, neutral, and low‐cost catalytic system with high TONs. DFT calculations afford a rationale toward the formation of the products and indicate that the selective insertion of the double bond of cyclopropenes into the C‐Pd bond of ambidentate Pd complex and the subsequent nonclassical β‐C elimination promoted by 1,4‐palladium migration are critical for the success of the reaction. 1,2‐Alkynylallylation of a specific C−C σ bond in cyclopropenes was realized by a simple, neutral, low‐cost palladium catalytic system with high TONs. This decarboxylative reorganization reaction is an efficient way to construct highly functionalized dienynes in excellent regio‐ and stereoselectivity. A nonclassical β‐C elimination promoted by 1,4‐palladium migration was described herein for the first time.