DOI: 10.1002/chem.201405564
Cover Profile
Lewis and Brønsted Acid Cocatalyzed Reductive Deoxyallenylation of Propargylic Alcohols with 2-Nitrobenzenesulfonylhydrazide
Invited for the cover of this issue is the group of Prof. Xihe Bi at Northeast Normal University, China. The cover illustrates the reductive deoxyallenylation of challenging sterically hindered tertiary propargylic alcohols, through the reaction with 2nitrobenzenesulfonylhydrazide (NBSH), by the combined use of FeF3 and HOTf catalysts. Read the full text of the article at 10.1002/chem.201404692.
Briefly, how would you describe your research? Considering the good availability of propargylic alcohols and the simplicity of operation, our method provides a practical and valuable tool for the preparation of a variety of mono-, di-, and trisubstituted allenes.
pothesis was realized experimentally, and a practical reductive deoxyallenylation reaction, suitable for secondary and tertiary propargylic alcohols, was discovered.
What prompted you to investigate this topic/problem? The reductive deoxyallenylation of propargylic alcohols is an extremely convenient approach to allenes. However, reliable protocols for such transformations are quite rare. In 1996, Myers and Zheng (J. Am. Chem. Soc. 1996, 118, 4492–4493) reported the reductive deoxyallenylation of propargylic alcohols with sulfonylhydrazine under Mitsunobu reaction conditions. However, only the less sterically hindered primary and secondary propargylic alcohols can be applied to this protocol. Our group is focused on the development of novel reactions by the strategic use of functionalized alkynes, and the challenge of developing an efficient reductive deoxyallenylation suitable for sterically hindered propargylic alcohols attracted our attention
What was the biggest challenge (on the way to the results presented in this paper)? We envisaged that an acidic catalyst could induce the ionization of propargylic alcohols to form a carbocation intermediate, which is intercepted by NBSH to give a hydrazide intermediate that is essential for subsequent allenation. Owing to the instability of the carbocation, one of the biggest challenges of this process was the preparation of alkyl allenes from alkyl propargylic alcohols. To overcome this challenge, we conceived that the superacid catalyst system, comprising a Lewis acid and Brønsted acid conjugate, such as FeCl3 and HOTf, could promote the ionization of the propargylic alcohols and form carbocation intermediates. Delightfully, this hyChem. Eur. J. 2014, 20, 17229
17229
2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Cover Profile
Lewis and Brønsted Acid Cocatalyzed Reductive Deoxyallenylation of Propargylic Alcohols with 2-Nitrobenzenesulfonylhydrazide
Invited for the cover of this issue is the group of Prof. Xihe Bi at Northeast Normal University, China. The cover illustrates the reductive deoxyallenylation of challenging sterically hindered tertiary propargylic alcohols, through the reaction with 2nitrobenzenesulfonylhydrazide (NBSH), by the combined use of FeF3 and HOTf catalysts. Read the full text of the article at 10.1002/chem.201404692.
Briefly, how would you describe your research? Considering the good availability of propargylic alcohols and the simplicity of operation, our method provides a practical and valuable tool for the preparation of a variety of mono-, di-, and trisubstituted allenes.
pothesis was realized experimentally, and a practical reductive deoxyallenylation reaction, suitable for secondary and tertiary propargylic alcohols, was discovered.
What prompted you to investigate this topic/problem? The reductive deoxyallenylation of propargylic alcohols is an extremely convenient approach to allenes. However, reliable protocols for such transformations are quite rare. In 1996, Myers and Zheng (J. Am. Chem. Soc. 1996, 118, 4492–4493) reported the reductive deoxyallenylation of propargylic alcohols with sulfonylhydrazine under Mitsunobu reaction conditions. However, only the less sterically hindered primary and secondary propargylic alcohols can be applied to this protocol. Our group is focused on the development of novel reactions by the strategic use of functionalized alkynes, and the challenge of developing an efficient reductive deoxyallenylation suitable for sterically hindered propargylic alcohols attracted our attention
What was the biggest challenge (on the way to the results presented in this paper)? We envisaged that an acidic catalyst could induce the ionization of propargylic alcohols to form a carbocation intermediate, which is intercepted by NBSH to give a hydrazide intermediate that is essential for subsequent allenation. Owing to the instability of the carbocation, one of the biggest challenges of this process was the preparation of alkyl allenes from alkyl propargylic alcohols. To overcome this challenge, we conceived that the superacid catalyst system, comprising a Lewis acid and Brønsted acid conjugate, such as FeCl3 and HOTf, could promote the ionization of the propargylic alcohols and form carbocation intermediates. Delightfully, this hyChem. Eur. J. 2014, 20, 17229
17229
2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
