84449-06-9Relevant academic research and scientific papers
Enantioselective total synthesis of callipeltoside A: two approaches to the macrolactone fragment
Evans, David A.,Burch, Jason D.,Hu, Essa,Jaeschke, Georg
, p. 4671 - 4699 (2008/09/21)
The enantioselective total synthesis of callipeltoside A is described. Two syntheses of the macrolactone subunit are included: the first relies upon an Ireland-Claisen rearrangement to generate the trisubstituted olefin geometry and the second utilizes an enantioselective vinylogous aldol reaction for this purpose. Enantioselective syntheses of the sugar and chlorocyclopropane side chain fragments are also disclosed. The relative and absolute stereochemistry of this natural product was determined by fragment coupling with the two enantiomers of the side chain fragment.
An aldol-based approach to the asymmetric synthesis of L-callipeltose, the deoxyamino sugar of L-callipeltoside A.
Evans,Hu,Tedrow
, p. 3133 - 3136 (2007/10/03)
[reaction: see text] The L-callipeltose subunit of L-callipeltoside A has been synthesized in 10 steps and 13% overall yield from D-threonine. The key steps are a highly diastereoselective Felkin anti aldol addition to a methyl ketone and a selective methylation of a secondary alcohol in the presence of a secondary carbamate.
HIGH-PRESSURE CYCLOADDITION OF 1-METHOXY-1,3-BUTADIENE TO N,O-PROTECTED D-THREONINALS AND D-ALLO-THREONINALS
Golebiowski, A.,Jurczak, J.
, p. 1037 - 1044 (2007/10/02)
High-pressure cycloadditions of trans-1-methoxy-1,3-butadiene (3) to N,O-protected D-allo-threoninals (4) and D-threoninals (8) were studied.In all cases, 5,6-syn-adducts were the major products.The results are explained by α-chelation with Eu(fod)3
Routes to Mitomycins. Chirospecific Synthesis of Aziridinomitosenes
Shaw, Kenneth J.,Luly, Jay R.,Rapoport, Henry
, p. 4515 - 4523 (2007/10/02)
The syntheses of ethyl (1R,2R)-1,2-(N-benzylaziridino)-7-methoxy-6-methyl-2,3,5,8-tetrahydro-5,8-dioxo-1H-pyrroloindole-9-carboxylate (59) and a regioisomeric aziridinoindoloquinone 60 are presented.Aziridine ring closure on a tricyclic indoloquinone nucleus and on monocyclic pyrrolidine derivatives was unsuccessful but did succeed with the acyclic educt.Thus the synthesis of the target aziridinomitosene was achieved by aziridine ring closure on the asymmetric 2-amino-3-hydroxy-4-azidobutanoate 49 followed by homologation and reductive ring closure to the bicyclic aziridinopyrrolidine 54.Subsequent reduction, regiospecific addition to 2,3-dibromo-5-methoxy-6-methylbenzoquinone (27), photochemical rearrangement, oxidation, and palladium-catalyzed ring closure afforded the (R,R)-aziridinomitosene 59.Regioisomeric aziridinoindoloquinone 60 was obtained directly by the addition of bicyclic aziridine 54 to dibromoquinone 27 followed by copper(II)-catalyzed ring closure.
OXYDATION OF BENZYLOXYCARBONYL THREONINE AND SERINE METHYL ESTERS TO AN OXAMATE DERIVATIVE
Stachulski, Andrew V.
, p. 3789 - 3790 (2007/10/02)
Both benzyloxycarbonyl threonine and serine methyl esters, when subjected to oxidation with reagents based on chromium(VI) oxide, gave rise to the same N-protected methyl oxamate, whose structure was confirmed by independent preparation.
