816454-36-1Relevant articles and documents
Diazepane Carboxylates as Organocatalysts in the Diels–Alder Reaction of α-Substituted Enals
H?ggman, Nicklas O.,Zank, Benjamin,Jun, HyunJune,Kaldre, Dainis,Gleason, James L.
supporting information, p. 5412 - 5416 (2018/10/20)
Ethyl diazepane carboxylate efficiently catalyzes the Diels–Alder cycloaddition of α-substituted-α,β-unsaturated aldehydes via iminium ion organocatalysis. The reaction is applicable to a range of dienes and dienophiles and generally proceeds at room temperature in the presence of 5 mol-% catalyst and 2.5 mol-% triflic acid co-catalyst. The incorporation of a stereogenic center on the diazepane backbone in combination with a menthyl carbamate produces a catalyst which affords enantioselectivities of 70–95 % ee for the cycloaddition of cyclopentadiene with a range of dienophiles. The enantioselectivity is rationalized via a transition state in which electrostatic stabilization by the carboxylate directs the diene to the more hindered face of the dienophile.
