Acylboronate esters/trifluoroborates represent an elusive class of boronates that are of increasing interest for both fundamental study as well as applications at the interface of chemistry and biology. Their preparation has been limited by the use of strongly basic anions, often introduced in multistep reactions. Herein, we demonstrate the facile preparation of acylboronate N-methyliminodiacetyl (MIDA) esters from alkenyl-2-boronate esters through mild dihydroxylation and meta-periodate cleavage. Given the well-known functional-group tolerance of this mild reaction sequence and the availability of alkenyl-2-boronates, this method should greatly increase access to acylboronate MIDA esters.
Acylboronate esters/trifluoroborates represent an elusive class of boronates that are of increasing interest for both fundamental study as well as applications at the interface of chemistry and biology.T heir preparation has been limited by the use of strongly basic anions,o ften introduced in multistep reactions.H erein, we demonstrate the facile preparation of acylboronate N-methyliminodiacetyl (MIDA) esters from alkenyl-2-boronate esters through mild dihydroxylation and meta-periodate cleavage.G iven the well-known functionalgroup tolerance of this mild reaction sequence and the availability of alkenyl-2-boronates,this method should greatly increase access to acylboronate MIDAesters. Scheme 4. Conversion of 1,2-dihydroxy MIDA boronate 2d into the benzoylboronate MIDA ester 3d.Scheme 5. Substrate scope for oxidative cleavage of 1,2-dihydroxy MIDA boronates. * = due to poor solubility of 2c in DCM, this reaction was carried out in CH 2 Cl 2 /MeCN/H 2 O10:10:1 (v/v/v).
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