Synfacts 2013; 9(1): 0098
DOI: 10.1055/s-0032-1317905
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart · New York

Frustrated Lewis Pairs for Catalytic Hydrogenation of Allenes and Alkenes

Contributor(s):
Benjamin List
,
Ji-Woong Lee
Inés B, Palomas D, Holle S, Steinberg S, Nicasio JA, Alcarazo M * Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany
Metal-Free Hydrogenation of Electron-Poor Allenes and Alkenes.

Angew. Chem. Int. Ed. 2012;
51: 12367-12369
Further Information

Publication History

Publication Date:
17 December 2012 (online)

 

Significance

The Alcarazo group reports a frustrated Lewis pair (FLP)-catalyzed hydrogenation reaction of electron-poor allenes and alkenes. The reduced products were obtained with good to ­excellent yield and high chemoselectivity by ­employing DABCO–B(C6F5)3 as a catalyst pair (10–15 mol%).


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Comment

To overcome the inherent reactivity of electron-rich allenes to cyclize to Friedel–Crafts products 1 in the presence Brønsted acids and/or Lewis acids, the authors employ electron-poor substrates to facilitate FLP-catalyzed hydrogenation to the desired product 2. According to the mechanistic studies, [DABCO–H]+ might act as a hydrogen-bond donor to activate the substrate. The hydride from the borohydride is transferred via 1,4-addition.


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