Brønsted Acid Tuned, Lewis Base Promoted [4 + 2] Annulation Reactions of Allenoates with Electron‐Deficient Olefins

The selective formation of an annulated 4H‐pyran from an allenoate and an olefin demonstrated the dual roles of triethylenediamine (DABCO) in both Lewis base promoted [4 + 2] annulation and Brønsted base mediated C=C isomerization. Interestingly, the role of the Brønsted base could be quenched selec...

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Bibliographic Details
Published in:European journal of organic chemistry 2018-09, Vol.2018 (35), p.4917-4925
Main Authors: Xi, Qiu‐Zhen, Gan, Zhen‐Jie, Li, Er‐Qing, Duan, Zheng
Format: Article
Language:English
Subjects:
[4+2] Annulation
Alkenes
Allenoates
Brønsted acids
Chemical reactions
Isomerization
Lewis base
Lewis bases
Organic chemistry
Organocatalysis
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Summary:The selective formation of an annulated 4H‐pyran from an allenoate and an olefin demonstrated the dual roles of triethylenediamine (DABCO) in both Lewis base promoted [4 + 2] annulation and Brønsted base mediated C=C isomerization. Interestingly, the role of the Brønsted base could be quenched selectively with the presence of a Brønsted acid (PhCO2H), and annulated 3,4‐dihydro‐2H‐pyran was obtained as the major product. The selective formation of an annulated 4H‐pyran from an allenoate and an olefin demonstrates the dual roles of triethylenediamine (DABCO) in both Lewis base promoted [4 + 2] annulation and Brønsted base mediated C=C isomerization. The role of the Brønsted base could be quenched selectively with the presence of a Brønsted acid (PhCO2H).
ISSN:1434-193X
1099-0690
DOI:10.1002/ejoc.201800917