The LANCA three-component reaction to highly substituted β-ketoenamides – versatile intermediates for the synthesis of functionalized pyridine, pyrimidine, oxazole and quinoxaline derivatives

• Tilman Lechel,
• Roopender Kumar,
• Mrinal K. Bera,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2019, 15, 655–678, doi:10.3762/bjoc.15.61

• -substituted oxazole derivatives OX. Hydrogenolyses of benzyloxy-substituted β-ketoenamides KE52 and KE54 to 1,2-diketone DK14 and to diastereomeric α-hydroxy-β-amino ketones 9. Conversions of 2,4-dicyclopropyl-substituted oxazole OX7 into oxazole derivatives OX18–20 (PPA = polyphosphoric acid). Syntheses of

Synthesis of rigid p-terphenyl-linked carbohydrate mimetics

• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 1749–1758, doi:10.3762/bjoc.10.182

• and of trityl-protected bicyclic 1,2-oxazine 16. Conditions: a) SnCl4, CH3CN, 18 h, −30 °C → rt, b) 1) L-selectride, THF, 4 h, −15 °C, dr 72:28; 2) separation by column chromatography (silica gel, hexanes/EtOAc 1:1 → 1:2); c) TrtCl, DMAP, pyridine, 3 d, rt. Hydrogenolyses of bicyclic 1,2-oxazine

Synthesis of new enantiopure poly(hydroxy)aminooxepanes as building blocks for multivalent carbohydrate mimetics

• Léa Bouché,
• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 213–223, doi:10.3762/bjoc.10.17

• crucial final palladium-catalyzed hydrogenolysis of the 1,2-oxazine moiety was optimized resulting in a reasonably efficient approach to a series of new seven-membered carbohydrate mimetics. Keywords: aminooxepanes; carbohydrate mimetics; hydrogenolyses; Lewis acid-induced; lithiated allenes; nitrones

• was obtained in 90% yield (Scheme 10). Under these optimized reaction conditions other hydrogenolyses were studied. p-Bromophenyl-substituted triol 16 was transformed into the corresponding poly(hydroxy)aminooxepane derivative 31 in 73% yield. As expected, the bromo substituent of the aryl group was

• effect spectroscopy] Proposed structures of the observed side products 29 and 30 during the hydrogenolyses of 14 and 15. General approach to enantiopure the poly(hydroxy)aminopyrans D (n = 0) and the aminooxepanes D (n = 1) by [3 + 3]-cyclization of the (Z)-nitrones A with lithiated TMSE-allene followed