On September 17, 2001, Stavenger, Robert A.; Schreiber, Stuart L. published an article.SDS of cas: 929-37-3 The title of the article was Asymmetric catalysis in diversity-oriented organic synthesis: Enantioselective synthesis of 4320 encoded and spatially segregated dihydropyrancarboxamides. And the article contained the following:
Dihydropyrancarboxylates were prepared on solid-phase by stereoselective and enantioselective hetero Diels-Alder cycloaddition of β,γ-unsaturated-α-keto esters to resin-bound vinyl ethers in the presence of nonracemic copper bis(oxazoline) catalysts as intermediates in the preparation of an encoded combinatorial library of dihydropyrancarboxamides. Hydroxy-substituted vinyl ethers were prepared; the vinyl ethers were attached by treatment of silyl-substituted polystyrene resin macrobeads with triflic acid followed by addition of the hydroxy-substituted vinyl ethers to the resin-bound silyl triflate; the resin-bound vinyl ethers were treated with chloroarom. diazoketones in the presence of dirhodium tetraacetate to give tagged resin-bound vinyl ethers which could be later identified by LC-MS. Treatment of resin-bound vinyl ethers such as I with the heterodienes (E)-RCH:CHCOCO2CH2CH:CH2 (R = Me2CH, Ph, 2-fluorenyl, 4-MeO2CC6H4, 5-benzo-1,3-dioxolanyl, 3-thienyl, 3-benzofuranyl, 1-acetyl-3-indolyl, 4-oxo-3-benzopyranyl, 1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydropyrazolyl) in the presence of the bis(oxazoline) II (or its enantiomer) and copper (II) triflate followed by cleavage of the resin with HF•pyridine gives nonracemic dihydropyrancarboxylates such as III (or their enantiomers) in >5:1 diastereoselectivities and >30:1 enantioselectivities. The resin-bound dihydropyrancarboxylates could be tagged with a second chloroarom. diazoketone, deallylated with tetrakis(triphenylphosphine)palladium and thiosalicylic acid in THF, coupled with primary and secondary amines with the benzotriazolyloxyphosphonium salt PyBOP and diisopropylethylamine, and cleaved from the resin with HF•pyridine to give an encoded combinatorial library of natural product-like nonracemic dihydropyrancarboxamides (no data). E.g., treatment of the silyl-substituted polystyrene resin with triflic acid followed by the addition of sulfonamide-substituted vinyl ether I with lutidine gave a resin-bound vinyl ether; the vinyl ether resin was added to unsaturated ketoester (E)-Me2CHCH:CHCOCO2CH2CH:CH2 and mol. sieves under argon; addition of THF and a solution of II and copper triflate in THF and stirring gave a resin-bound nonracemic dihydropyrancarboxylate which was cleaved from the resin with HF•pyridine to give III in >95% purity and in >16:1 diastereo- and enantioselectivities. Cleavage of a subset of the dihydropyrancarboxamide-containing beads and anal. by LC-MS indicated that 104 of the 108 sample compounds were isolated in >75% purity. The use of asym. synthesis of natural product-like libraries on encoded beads allows for the use of stereochem. as a diversity element in the preparation of combinatorial libraries; the prepared libraries are produced in a form amenable to robot-controlled biol. testing. The experimental process involved the reaction of 2-(2-(Vinyloxy)ethoxy)ethanol(cas: 929-37-3).SDS of cas: 929-37-3
The Article related to dihydropyrancarboxylate stereoselective enantioselective preparation intermediate combinatorial library, dihydropyrancarboxamide stereoselective enantioselective preparation combinatorial library, copper bisoxazoline catalyst enantioselective cycloaddition unsaturated ketoester vinyl ether and other aspects.SDS of cas: 929-37-3
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