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Beta-hydroxy amides 6 and 7 were treated with triphenylphosphonium anhydride trifluoromethane sulfonate (3), or the cyclic analogue 4, to generate 2-oxazolines 5 and 8 under mild conditions. The reaction was optimised by examining the number of equivalents of reagents 3 or 4, or diisopropylethyl amine required to best effect cyclisation. The effects of… (More)
A series of morpholine substituted amino acids (phenylalanine, leucine, lysine and glutamic acid) was synthesized. A fragment-based screening approach was then used to evaluate a series of small heterocycles, including morpholine, oxazoline, dihydro-1,3-oxazine, tetrahydro-1,3-oxazepine, thiazoline, tetrahydro-1,3-pyrimidine, tetrahydro-1,3-diazepine and… (More)
Reaction of hexa-N-Boc neomycin B with TPP and DIAD in toluene results in the formation of an epoxide in ring IV, not an aziridine or azetidine as previously reported.
The alkoxytriphenylphosphonium ion intermediate of the Mitsunobu reaction can be generated using the Hendrickson reagent, triphenylphosphonium anhydride trifluoromethanesulfonate, 1. Strangely, while the reagent 1 can be used in place of the Mitsunobu reagents (triphenylphosphine and a dialkylazodicarboxylate) for the esterification of primary alcohols,… (More)
The title compound, C(13)H(18)N(2)O(4), crystallizes as discrete mol-ecules associated as N-H⋯O hydrogen-bonded dimers disposed about a crystallographic inversion centre. The structure is the first solid-state structure for a 3-acetyl-pyridone without C-4 to C-6 substituents. The amide subsituent at C-3 is coplanar with the pyridone ring, while the… (More)
The racemic title compound, C(9)H(11)NO(4)·H(2)O, a tricyclic rearranged amino-norbornane dicarb-oxy-lic acid, is a conformationally rigid analogue of glutamic acid and exists as an ammonium-carboxyl-ate zwitterion, with the bridghead carb-oxy-lic acid group anti-related. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds involving the ammonium, carb-oxy-lic… (More)
Bis-phosphine oxides can be selectively reduced to bis-phosphine monoxides under exceptionally mild conditions using triflic anhydride and a thiol.