1257228-77-5Relevant articles and documents
Amine-catalyzed asymmetric (3 + 3) annulations of β′-acetoxy allenoates: Enantioselective synthesis of 4H-pyrans
Ni, Chunjie,Tong, Xiaofeng
supporting information, p. 7872 - 7875 (2016/07/07)
The asymmetric (3 + 3) annulations of β′-acetoxy allenoates with either 3-oxo-nitriles or pyrazolones have been realized by using 6′-deoxy-6′-[(l)-N,N-(2,2′-oxidiethyl)-valine amido]quinine (6h) as the catalyst. The three functions of catalyst 6h, including Lewis base (quinuclidine N), H-bond donor (amide NH), and Br?nsted base (morpholine N), cooperatively take crucial roles on the chemo- and enantioselectivity, allowing for the construction of 4H-pyran and 4H-pyrano[2,3-c]pyrazole in high yields and enantioselectivity.