Asymmetric Hetero‐Diels–Alder Reaction of Danishefsky’s Diene with α‐Ketoesters and Isatins Catalyzed by a Chiral N,N′‐Dioxide/Magnesium(II) Complex

Abstract

A highly enantioselective hetero-Diels-Alder reaction of Danishefsky's diene with α-ketoesters and isatins has been realized by using a chiral N,N'-dioxide/Mg(II) complex. In the presence of only 0.1-0.5 mol % catalyst, a series of substrates were transformed into the corresponding tetrasubstituted 2,3-dihydropyran-4-ones in up to 99 % yield and more than 99 % ee in two hours.

Copper-Catalyzed Enantioselective Hetero-Diels–Alder Reaction of Danishefsky’s Diene with Glyoxals

“…After that, the HDA reaction of α-carbonyl esters was further developed by Loh . Recently, a chiral 3,3-dibromo-BINOL-Zn complex was found to be an efficient catalyst in various HDA reactions by Ding et al Moreover, impressive work on the HDA reaction of substituted Danishefsky’s diene with aldehydes had been achieved by Feng’s group by using a chiral N , N -dioxide/In­(OTf) 3 catalyst . However, to the best of our knowledge, the HDA reaction of Danishefsky’s diene with glyoxals has received far less attention.…”

Stereoselective synthesis and applications of spirocyclic oxindoles

“…Feng has employed a Mg/chiral N,N′dioxide catalyst system for a hetero Diels-Alder reaction. 405 Li has recently reported a Bi/chiral phosphoric acid 77 catalysed allylation of isatins which could be further elaborated to spiroTHP products (Scheme 79). 406 Arai has employed a Ts-PyBidine-Ni complex to catalyse the asymmetric addition of indole to 3-ylidene oxindoles and a highly diastereoselective iodocyclisation to 6-membered products was developed using cat.…”

Magnesium Catalysis in Asymmetric Synthesis

“…The desired 2,3-dihydropyran-4-ones could be obtained with extremely high enantioselectivities because of the well-controlled chiral environment provided by the dioxide/Mg(II) system. 42 Notably, the catalytic system is so efficient that in most cases, the catalyst loading was only 0.1 mol %, which is unusually low for a Lewis acid-mediated reaction. Later, the same group also reported asymmetric hetero-Diels-Alder reactions of Brassard's diene under similar conditions.…”