Asymmetric pyrone Diels–Alder reactions enabled by dienamine catalysis
作者:Charles J. F. Cole、Lilia Fuentes、Scott A. Snyder
DOI:10.1039/c9sc05738b
日期:——
utilizing pyrone dienes to create molecular complexity via Diels–Alder reactions with varied dienophiles, few examples of effective catalytic, asymmetric variants of this process have been developed. Herein, we show that the use of Jørgensen–Hayashi-type catalysts can convert an array of α,β-unsaturated aldehydes into chiral dienamines that can formally add in a Diels–Alder fashion to a number of electron-deficient
Synthese von 2(1<i>H</i>)-Pyridonen aus 2<i>H</i>-Pyran-2-onen
作者:Vratislav Kvita
DOI:10.1055/s-1991-26600
日期:——
Synthesis of 2(1H)-Pyridones From 2H-Pyran-2-ones 5-Substituted and 4,5-disubstituted 2(1H)-pyridones (13 examples) with formyl, acyl, alkoxycarbonyl, and trifluoromethyl groups in the 5 position were prepared in 16-97% yield by amination of the corresponding 2H-pyran-2-ones with hexamethyldisilazane or alkyl(trimethylsilyl)amines.
tandem [3 + 2] cycloaddition/Cope rearrangementreaction of vinylethylene carbonates (VECs) with coumalates or pyrones. Under mild conditions, palladium-catalyzed asymmetric tandem reaction of various substituted VECs and coumalates or pyrones proceeds smoothly to produce the corresponding medium-sized heterocyclic compounds in high yields with very high enantioselectivities. Moreover, the reaction on the
ilyl)phenyl]iodonium triflates were prepared for the generation of benzynes bearing ketone function. Treatment of the iodonium triflates with Bu4NF in CH2Cl2 in the presence of furan at room temperature gave 6-acyl-1,4-epoxy-1,4-dihydronaphthalenes in high yields. The mild conditions and the tolerance of the ketone function on benzyne generation are attributable to the advantage of hypervalent iodine