- Synthesis of acyclic ketones by catalytic, bidirectional homologation of formaldehyde with nonstabilized diazoalkanes. Application of a chiral diazomethyl(pyrrolidine) in total syntheses of erythroxylon alkaloids
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This work offers a catalytic approach to convergent ketone assembly based upon formal and tandem C-H insertion of diazoalkanes in the presence of limiting amounts of monomeric formaldehyde, which is easily generated as a gas by thermolysis of the inexpensive and abundant paraformaldehyde (~30 USD/kg). The method forms di-, tri-, and even tetrasubstituted acetones with high efficiency, and it has streamlined a synthesis of (-)-dihydrocuscohygrine in which the absolute stereochemistry of a proline-based starting material is preserved. Assisted by the advent of new protocols for hydrazone oxidation, we also provide full details on handling non-carbonyl-stabilized diazo compounds.
- Wommack, Andrew J.,Kingsbury, Jason S.
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p. 10573 - 10587
(2013/11/19)
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- Concise total synthesis of (-)-deoxocuscohygrine and (-)- dihydrocuscohygrine
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(Chemical Equation Presented) The concise enantioselective total synthesis of C2-asymmetrical (-)-deoxocuscohygrine and (-)-dihydrocuscohygrine are described. Double-diastereoselective additions of normal Grignard reagent to bis(1,3-oxazolidine
- Yamauchi, Takayasu,Hagiwara, Sachi,Higashiyama, Kimio
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experimental part
p. 9784 - 9787
(2009/04/07)
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- Total synthesis of (+)-dihydrocuscohygrine and cuscohygrine
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The first enantioselective synthesis of (+)-dihydrocuscohygrine 1 and cuscohygrine 2 is presented. 1 was obtained in nine steps and 30% overall yield with a ruthenium-catalyzed tandem ring rearrangement metathesis key step starting from enantiomerically pure cycloheptene-1,3,5-triol derivative 6. The unknown absolute configuration of natural dihydrocuscohygrine 1 could be determined as (S,S)-(-). Cuscohygrine 2 was obtained by Jones oxidation of 1 in quantitative yield but unfortunately with complete epimerization.
- Stapper, Christian,Blechert, Siegfried
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p. 6456 - 6460
(2007/10/03)
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- ISOLATION OF DIHYDROCUSCOHYGRINE FROM PERUVIAN COCA LEAVES
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Key Word Index-Erythroxylon coca; Erythroxylaceae; coca leaves; alkaloids; cuscohygrine; (-)-dihydrocuscohygrine; identification.Abstract-An investigation of the alkaloidal fraction of Erythroxylon coca leaves, collected in Peru, has resulted in the isolation and characterization of cuscohygrine and (-)-dihydrocuscohygrine.The structure of (-)-dihydrocuscohygrine was deduced by spectral and chemical means.
- Turner, C. E.,Elsohly, M. A.,Hanus, L.,Elsohly, H. N.
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p. 1403 - 1406
(2007/10/02)
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