92052-73-8Relevant academic research and scientific papers
Enantioselective total synthesis and confirmation of the absolute and relative stereochemistry of streptorubin B
Hu, Dennis X.,Clift, Michael D.,Lazarski, Kiel E.,Thomson, Regan J.
supporting information; experimental part, p. 1799 - 1804 (2011/04/15)
The enantioselective total synthesis of the pyrrolophane natural product streptorubin B is described. Key steps in the concise route include the application of a one-pot enantioselective aldol cyclization/Wittig reaction and an anionic oxy-Cope rearrangement to forge the crucial 10-membered ring. Comparisons between CD spectra of synthetic and natural samples of streptorubin B coupled with X-ray crystallography allowed for the determination of the absolute stereochemistry of this natural product for the first time. These studies also provided unambiguous proof of the relative configuration between the butyl side chain and the bispyrrole subunit. Additional studies revealed a novel atropstereoselective Paal-Knorr pyrrole condensation and provided fundamental experimental insight into the barrier for atropisomerization of the natural product.
Glycosidase inhibitors: Synthesis of enantiomerically pure aza-sugars from Schiff base amino esters via tandem reduction-alkenylation and osmylation
Polt, Robin,Sames, Dalibor,Chruma, Jason
, p. 6147 - 6158 (2007/10/03)
Nitrogen-in-the-ring 'aza-sugars' have been synthesized in enantiomerically pure form from the amino acid L-alanine in excellent overall yield. The O'Donnell's Schiff base of L-alanine methyl ester 9a was converted to aza-sugar L-fuco-1-deoxy-nojirimycin, 18, and to the epimer L-gulo-1- deoxy-nojirimycin, 20, in eight steps. The overall yields were 20 and 29%, respectively. The methodology for the efficient generation of silyl- and benzyl-protected (E)-3-lithio-2-propen-1-ols, and the use of these alkenyllithiums with iBu5Al2H as nucleophiles in the threo-selective tandem reduction-alkenylation of the Schiff base esters is described. Osmium- catalyzed cis-oxygenation of the resulting olefin products was selective for the galacto (fuco) amino polyols in all cases for the acyclic olefins, and was gulo-selective for the cyclic D-4,5-dihydropyridine pivalate, 17c. TEMPO- NaOCl was selective for oxidation of the primary position of the acyclic Schiff bases, and allowed for minimal protection/deprotection of the intermediates. The resulting N-benzhydryl heterocycles were easily deprotected with H2-Pd at atmospheric pressure.
A route to the pyrrolo[1,2-a]indolenine ring system via intermolecular organolithium addition to an oxindole
Jones,Storey
, p. 4901 - 4906 (2007/10/02)
A synthesis of the pyrrolo[1,2 a]indolenine 6 in four steps from N-benzyl-3,3-dimethyloxindole 2 is presented involving an organolithium addition to the oxindole carbonyl group. Additions of vinyllithiums to the oxindole 2 are presented.
