Alkoxy- and hydroxycyclization of enynes catalyzed by Pd(II) and Pt(II) catalysts

Abstract

The development of a novel reaction ideal in terms of atom economy was achieved. The scope of the reaction was evaluated in the presence of Pd and Pt catalysts. The first enantioselective Pt-promoted enyne carboalkoxycyclization was developed in up to 85 % stereoselectivity. This ideal atom-economical reaction afforded the corresponding functionalized five-membered carbo-and heterocycles in good to excellent yields. The use of silver salts combined with (R)-Ph-BINEPINE, a monophosphane atropisomeric ligand, was found to be the best-suited combination for moderate to high enantioselectivities on carbonated and nitrogenated substrates.

Asymmetric Au-catalyzed cycloisomerization of 1,6-enynes: An entry to bicyclo[4.1.0]heptene

“…The corresponding substituted alkynes 2b–e [ 46 ] were isolated in 71–85% yield. An analogous 1,6-enyne 6 [ 64 ] was also reacted with 3-bromoiodobenzene under the same reaction conditions and led to the formation of substrate 2f in 58% isolated yield. We also envisaged preparing two trisubstituted alkenes 2g and 2h by an alkylation/Sonogashira sequence starting from commercially available substrates 7 and 8 .…”

Renoprotective effect of Tanshinone IIA, an active component of Salvia miltiorrhiza, on rats with chronic kidney disease

“…In 2006, Genêt et al. developed enantioselective platinum‐catalyzed domino hydroxy and alkoxycyclization reactions of 1,6‐enynes 102. As shown in Scheme , when the reaction of 1,6‐enynes 146a – d with water or methanol was catalyzed by a chiral platinum complex of ( R )‐Ph‐BINEPINE, a monophosphane atropisomeric ligand, in the presence of silver salts as additives, it afforded the corresponding functionalized carbo‐ and heterocycles 147a – d in moderate to high yields and good enantioselectivities of up to 85% ee .…”

Palladium-catalysed hydroxylation and alkoxylation

“…35 More recently Ba¨ckvall and co-workers reported the palladium-catalysed oxidative carbohydroxylation of allenesubstituted conjugated dienes (Scheme 21). 36 The starting material was reacted with p-benzoquinone in the presence of catalytic amounts of palladium trifluoroacetate in a mixture of water/THF as solvent.…”