Synthesis of Erythrina and related alkaloids. XVI Diels-Alder approach : Total synthesis of dl-erysotrine, dl-erythraline, dl-erysotramidine, dl-8-oxoerythraline and their 3-epimers.

Synthesis of erythrina and related alkaloids. 17. Total synthesis of dl-coccuvinine and dl-coccolinine

“…(7), who accomplished the first total synthesis of the abnormal-type erythrinan alkaloids by the method developed by Mondon et al (8,9), solved this problem by the introduction of an ethoxycarbamide group at the C(16) 'For part 16 see ref. 6. This paper also constitutes Part XXXIX of Dioxopyrrolines.…”

“…Thus, heating of 6 a with the diene in toluene at 1 30°C for 20 min afforded the adduct 7 a in 71% yield. The stereochemical assignment of the C(l) OTMS group as having the endo configuration results from comparison of the nrnr spectrum of 7 a with those of the adducts reported in the previous papers Can (6,12). Reduction of 7 a with lithium borohydride at -63OC occurred selectively at the C(7) keto group and treatment of the resulting alcohol with hydrochloric acid afforded the enone 8a in 56% yield.…”

“…We have recently developed a new effective synthetic route to the erythrinan alkaloids using Diels-Alder reaction of isoquinolinopyrrolinedione with 1,3-0-disubstituted butadiene as a key step (4)(5)(6). This method provides a short synthesis of these alkaloids, if the isoquinoline ring closure occurs at the meta position with respect to the methoxy group on the aromatic ring.…”

Synthesis and chemical transformations of 2,3-dihydropyrrole-2,3-diones annelated on the [a] side by azaheterocycles. (Review)

“…The review does not include data on the chemistry of isatins and their aza analogs, which were described in [8], or data on the cycloaddition of these pyrrolediones, which have been discussed before [1][2][3][4][5][6][7][9][10][11] and were reviewed in [11].…”

“…The reaction is usually conducted in an inert aprotic solvent (ether [7,[9][10][11], chloroform [9,12], dichloromethane [13], 1,2-dimethoxyethane [14], benzene [15,16], dioxane [17]) or in pyridine in the range of 0-100°C for 1.5-3.5 h. The yields of the desired products are as a rule good particularly if the enamine contains at least one electron-withdrawing substituent (a COR or COOR group); there has been are no mention of the isolation of side products.…”