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US 2014/0275504 A1Published application
Process for the preparation of certain triaryl rhamnose carbamates
AssigneeDow AgroSciences LLC
InventorsNatalie C. GIAMPIETRO, Lawrence C. CREEMER
Life of this patent
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Abstract
Aryl boronic esters containing the rhamnose carbamate moiety are prepared in good yield and without cleavage of the carbamate linkage by first contacting p-bromophenyl isocyanate with a tetrahydropyran-2-ol followed by reaction with a diboron compound.
Claims5
A compound of formula (III)
- wherein
- R, R1 and R2 independently represent C1-C4 alkyl, C3-C4 alkenyl or C1-C4 fluoroalkyl, and
- R3 and R4 independently represent H, C1-C4 alkyl, or when taken together form an ethylene or propylene group optionally substituted with from one to four CH3 groups.
A process for preparing a boronic ester of the formula (IIIa)
- wherein
- R, R1 and R2 independently represent C1-C4 alkyl, C3-C4 alkenyl or C1-C4 fluoroalkyl, and
- R3 and R4 independently represent C1-C4 alkyl, or when taken together form an ethylene or propylene group optionally substituted with from one to four CH3 groups, which comprises
- a) contacting p-bromophenyl isocyanate
- with a tetrahydropyran-2-ol of Formula (IV)
- wherein
- R, R1 and R2 independently represent C1-C4 alkyl, C3-C4 alkenyl or C1-C4 fluoroalkyl,
- in a polar aprotic solvent in the presence of cesium carbonate to form a carbamate of Formula (V)
- wherein R, R1 and R2 are as previously defined, and
- b) contacting the carbamate of Formula (V) with a diboron compound of Formula VI
- wherein R3 and R4 are as previously defined,
- in a polar aprotic solvent in the presence of a palladium catalyst and an alkali metal or alkaline earth metal acetate.
9 more elements
Dependencies are inferred from the claim text.