Ruthenium porphyrin catalyzed tandem sulfonium/ammonium ylide formation and [2,3]-sigmatropic rearrangement. A concise synthesis of (+/-)-platynecine.
meso-Tetrakis(p-tolyl)porphyrinatoruthenium(II) carbonyl, [Ru(II)(TTP)(CO)], can effect intermolecular sulfonium and ammonium ylide formation by catalytic decomposition of diazo compounds such as ethyl diazoacetate (EDA) in the presence of allyl sulfides and amines. Exclusive formation of [2,3]-sigmatropic rearrangement products (70-80% yields) was observed without [1,2]-rearrangement products being detected. The Ru-catalyzed reaction of EDA with disubstituted allyl sulfides such as crotyl sulfide produced an equimolar mixture of anti- and syn-2-(ethylthio)-3-methyl-4-pentenoic acid ethyl ester. The analogous "EDA + N,N-dimethylcrotylamine" reaction afforded a mixture of anti- and syn-2-(N,N-dimethylamino)-3-methyl-4-pentenoic acid ethyl esters with a diastereoselectivity of 3:1. The observed catalytic activity of [Ru(II)(TTP)(CO)] for the ylide [2,3]-sigmatropic rearrangement is comparable to the reported examples involving [Rh(2)(CH(3)CO(2))(4)] and [Cu(acac)(2)] as catalyst. Similarly, cyclic sulfonium and ammonium ylides can be produced by intramolecular reaction of a diazo group tethered to allyl sulfides and amines under the [Ru(II)(TTP)(CO)]-catalyzed reaction conditions. The subsequent [2,3]-sigmatropic rearrangement of the cyclic ylides furnished 2-allyl-substituted sulfur and nitrogen heterocycles in good yields (>90%). By employing [Ru(II)(TTP)(CO)] as catalyst, the cyclic ammonium ylide [2,3]-sigmatropic rearrangement reaction was successfully applied for the total synthesis of (+/-)-platynecine starting from cis-2-butenediol.
Zhou
Cong-Ying
CY
Department of Chemistry and Open Laboratory of Chemical Biology of the Institute of Molecular Technology for Drug Discovery and Synthesis, The University of Hong Kong, Pokfulam Road, Hong Kong.
Yu
Wing-Yiu
WY
Chan
Philip Wai Hong
PW
Che
Chi-Ming
CM
D002384:Catalysis; D006574:Heterocyclic Compounds, 2-Ring / Q000138:chemical synthesis*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000138:chemical synthesis*; D012428:Ruthenium / Q000737:chemistry*; D013237:Stereoisomerism; D013452:Sulfonium Compounds / Q000138:chemical synthesis*
D006574:Heterocyclic Compounds, 2-Ring; D009942:Organometallic Compounds; D011166:Porphyrins; D000644:Quaternary Ammonium Compounds; D013452:Sulfonium Compounds; D012428:Ruthenium; C494063:platynecine