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Total synthesis
About: Total synthesis is a research topic. Over the lifetime, 25578 publications have been published within this topic receiving 489319 citations.
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TL;DR: In this paper, a concise total synthesis of (+)-hyacinthacine A2, a polyhydroxylated pyrrolizidine alkaloid, is described using our recently discovered inversion of the C−N bond polarity in nitrones.
Abstract: A concise total synthesis of (+)-hyacinthacine A2, a polyhydroxylated pyrrolizidine alkaloid, is described using our recently discovered inversion of the C−N bond polarity in nitrones. In the key step, the diastereoselective reductive coupling of a l-xylose-derived cyclic nitrone with ethyl acrylate allowed the assembly of the bicyclic core of the target molecule, by way of a tandem formation of the C−C and C−N bonds. The method opens a novel, short, and general route for the synthesis of other pyrrolizidine alkaloids.
142 citations
TL;DR: Palladium-catalyzed cyclizations of aryl halides, vinyl halides and vinyl mflates with tethered alkenes have proven to be powerful reactions for forging congested quaternary carbon centers in complex organic molecules as mentioned in this paper.
Abstract: Palladium-catalyzed cyclizations of aryl halides, vinyl halides and vinyl mflates with tethered alkenes have proven to be powerful reactions for forging congested quaternary carbon centers in complex organic molecules. I'n some cases, the use of enantiopure ligands allows the new quaternary center to be formed with excellent enantioselectivity. The scope, stereochemical nuances and power of this organometallic chemistry is illustrated by briefly considering our recent total syntheses of (*)- pretazettine, (2)-tazettine, (-)- and (+)-morphine, (-)- and (+)-physostigmine, (&)- scopadulcic acid A and (*)-scopadulcic acid B.
141 citations
TL;DR: A practical Pd(II)/Pd(IV)-catalyzed carboxyl-directed C-H activation/C-O cyclization to construct biaryl lactones has been developed and the synthetic utility was demonstrated in an atom-economical and operationally convenient total synthesis of the natural product cannabinol.
141 citations
TL;DR: With this newly established methodology, asymmetric total synthesis of (-)-Mesembrine in high enantiomeric excess (98% ee) was accomplished.
Abstract: Desymmetrization of cyclohexadienones via aza-Michael reaction catalyzed by cinchonine derived thiourea has been realized to afford a series of highly enantioenriched pyrrolidine and morpholine derivatives in excellent yields and ees. With this newly established methodology, asymmetric total synthesis of (-)-Mesembrine in high enantiomeric excess (98% ee) was accomplished.
141 citations
TL;DR: A concise total synthesis of the potent cytotoxic marine natural products salicylihalamide A and B (la, b) is reported.
Abstract: A concise total synthesis of the potent cytotoxic marine natural products salicylihalamide A and B (la, b) is reported. Key steps of our approach were the asymmetric hydrogenation reactions of β-keto esters 18 and 32 catalyzed by [((S)-BINAP)Ru-Cl 2 ] 2 .NEt 3 and the cyclization of the macrolide core by ring closing olefin metathesis (RCM) using the "second-generation" ruthenium carbene complex 24 as the catalyst which bears an imidazol-2-ylidene ligand. The E/Z ratio obtained in this macrocyclization reaction was determined by the protecting groups at the remote phenolic OH group of the cyclization precursor. The elaboration of the resulting cycloalkene 37 into the final target involved a CrCl 2 -mediated synthesis of vinyliodide 49 which, after deprotection, did undergo a copper-catalyzed cross-coupling process with the (Z,Z)-configurated carboxamide 42 to form the labile enamide moiety of 1. Compound 42 was derived from a palladium-catalyzed Negishi coupling between butynylzinc chloride and 3-iodoacrylate 39 followed by a Lindlar reduction of enyne 40 thus obtained and a final aminolysis of the ester group.
141 citations