Pyrrolone derivatives

Fischer-type carbene complexes in the synthesis of furan, pyrrole, 5//-furanone, and 5//-pyrrolone derivatives 98YGK413. 

Octafluoroisobutylene reacts with acetone oxime to give pyrrolone derivative 1 via the intermediate formation of compound 2. 

Cycloaddition reactions of 2,3-diphenylcyclopropenone with a variety of cyclic imines gave bi- and tricyclic pyrrolone derivatives... 

Very recently, Petersen and Nielsen [44] could not only show that the nucle-ophihc trapping of the acyliminium ion can be conducted in an intramolecular manner but also extend the sequentially Ru-catalyzed RCM-isomerization sequence to exploit the heteroaromatic hydroxyl tautomer for an aldol condensation to give pyrrolone derivatives 22 (Scheme 12.14). The combination of RCM-isomerization-intermolecular nucleophilic trapping and the acid-catalyzed aldol condensation has been elegantly illustrated in the total synthesis of the antileukemic indole alkaloid violacein. 

Scheme 12.14 RCM-isomerization-aldol condensation synthesis of pyrrolone derivatives 22.

As our continued interest in reaction chemistiy of NSBVs, we envisioned NSBVs would show a different oxidation reaction pattern from that of normal aziridines and SBVs. The author found selective and efficient oxidation reaction of NSBVs by oxygen or V-oxide to afford A -bipyrrolone and mono-pyrrolone derivatives [64,65]. The C-N bond cleavage and C-H bond oxidation proceeded in the reaction process. Both A -bipyrrolones and mono-pyrrolones were further... 

A, 15) and 6-[ [l-[5-amino-5-arboxypentyl]-3- hydroxy-pyrrol-2-yl]-(E)-2-methylidene-5-methyl-l,2H-pyrrol-3-one-l-ly]-2-amino-hexanoic acid (dilysyldipyrrolone B, 6) They were novel pyrrolyl-methylidene-pyrrolone derivatives containing two lysine residues, which were named dilysyldipyrrolones A and B.14). Contributions of these compounds to a heated solution were estimated by the color dilution method. Dilysyldipyrrolones A and B contributed to about 5% and 10% of total color, respectively, while 4-hydroxy-5>methyl-2-furfurylidne 3(2H)-furanone contributed only to 0.05%. 

Bis-p-nitrophenyl malonate (55M29) reacts with a-alkylamino-isobutyr-onitriles in xylene to give derivatives (16b) of tetramic acids with yields of 30-50% (86UP1 88UP1). The reaction of derivatized malonic acids with a-amino acid esters to 3-alkoxycarbonyl-l,5-dihydro-4-hydroxy-2-pyrrolones presents the same problems (see Section III). (See Fig. 8.)... 

As demonstrated in Section I, numerous representatives of this type of compounds occur naturally. Such natural substances are commonly characterized by two special features, (a) The C-5 carbon atom of the pyrrolone ring is a stereo center that can be provided by natural derivatives of amino acids. (b) The acyl substituent at C-3 often includes a complex... 

A photochemical preparation of a Cephalotaxus alkaloid synthon (20) has been reported (Scheme 2).10 The readily accessible maleimide (17) was iodinated with iodine and silver trifluoroacetate, in 71% yield, and the resulting compound was transformed in two steps (70% overall yield) into the methylene-pyrrolone (18) by the action of methylmagnesium iodide followed by dehydration. Irradiation of (18) afforded (19) (46% yield), which, by successive hydrogenation and reduction with lithium aluminium hydride, gave the dihydro-pyrrolo[2,l-b][3]benzazepine (20). This derivative has served as a key intermediate in the total synthesis of cephalo-taxine described previously (see Vol. 7 of these Reports). 

Hydrogenolysis in the presence of Raney-Ni of derivatives 29 and 30, coming from Baylis-Hillman adducts of 3-isoxazole carbaldehydes, generated enaminones 31a,b that underwent ring-closure reactions to afford substituted 2-pyrrolidinones 32, 1,5-dihydro-2-pyrrolones 33, and iV-substituted pyrrolidines 34 in good yields <05JOC353>. 

Acid-catalysed cyclization of a 3-acylaminomethylquinoline through a Reissert compound gives a pyrrolone-fused derivative (review [2959a]). 

Refluxing the enaminones 149 with diphenylcyclopropenone in toluene gives first the adducts 150, which rearrange to the pyrrolones 151 in good yields. Scheme 39. Enaminones derived from dimedone give the corresponding spiro pyrrolones, but in low yields (80JOC5340). 

Kolbe conditions to give 914. Reduction with lithium aluminum hydride, acetonide formation (acetone, PTSA), and Collins oxidation furnishes aldehyde 915. A Homer—Emmons-type condensation of 915 with dienyl phosphonate 916 affords triene 917 in 50% yield. A Diels-Alder cycloaddition of 917 with L-phenylalanine-derived pyrrolone 918 (xylene, 170 °C, 4 days) produces a separable 4 1 mixture of 919 and the undesired regioisomer. Introduction of the methanol functionality and elaboration of the terminal isopropylidene group to a ra 5-a,j -unsaturated system completes the synthesis (Scheme 135) [203]. 

Six-membered Rings.— The versatility of 1,3-dipolar cycloadditions and of hetero-Diels-Alder reactions is, once again, used to great effect for the synthesis of 1,2-oxazine derivatives. Useful, multifunctionalized heterocycles are obtained by reaction of nitrile oxides with sulphoxonium allylides, followed by conversion of the initially formed furans (257) to oxazines (258) by treatment with tosic acid. Treatment with NEts causes migration of the alkoxycarbonyl group forming the pyrrolone (259). 

---