ABSTRACT
Structurally diverse carbocycles with two vicinal nitrogen-substituents were prepared in expedient three-component reactions from simple amines, aldehydes, and nitroalkenes. trans,trans-6-Nitrocyclohex-2-enyl amines were obtained in a one-pot domino reaction involving condensation, tautomerisation, conjugate addition, and nitro-Mannich cyclisation. Upon employment of less nucleophilic carboxamides, a concerted Diels-Alder cycloaddition mechanism operated to give the corresponding cis,trans-nitrocyclohexenyl amides. Both types of substituted carbocycles offer ample opportunities for chemical manipulations at the core and periphery. Ring oxidation with MnO2 affords substituted nitroarenes. Reduction with Zn/HCl provides access to various trans- and cis-diaminocyclohexenes, respectively, in a straight-forward manner. With enantiopure secondary amines, a two-step synthesis of chiral nitrocyclohexadienes was developed (82-94% ee).
ABSTRACT
An atropo-diastereoselective synthesis with dr up to 98/2 towards the biaryl subunit of vancomycin based on the use of enantiopure ß-hydroxysulfoxide derivatives as novel chiral auxiliary is reported.
Subject(s)
Vancomycin/chemistry , Molecular Structure , Stereoisomerism , Vancomycin/analogs & derivativesABSTRACT
A general and convenient protocol for the electrophilic borylation of aryl Grignard reagents prepared from arylbromides by direct insertion of magnesium in the presence of LiCl or by Mg/Br exchange with (i)PrMgCl·LiCl has been developed. Various aryl boronic acids were synthesized in a straightforward manner in excellent yields at 0 °C.
Subject(s)
Boronic Acids/chemistry , Hydrocarbons, Brominated/chemistry , Organometallic Compounds/chemistry , Amines/chemical synthesis , Amines/chemistry , Carbon Dioxide/chemical synthesis , Carbon Dioxide/chemistry , Coordination Complexes , Molecular Structure , StereoisomerismABSTRACT
Starting from branched para-benzoquinones a practical and highly flexible route is described for the preparation of unsaturated carbapyranoses. The potential of the synthesized galactose analogues to act as competitive inhibitors in lectin-carbohydrate interactions is investigated by means of Surface Plasmon Resonance (SPR) Spectroscopy.
