A concise synthesis of acylborons was achieved by ozonolysis of alkenyl MIDA (N-methyliminodiacetic acid) boronates. This reaction exhibits excellent functional-group tolerance and is applicable to various acyl MIDA boronates and potassium acyltrifluroborates (KATs) which could not be synthesized by previous methods. In addition, α-amino acylborons, which would be essential for peptide ligations, were prepared for the first time. The acylboron of l-alanine was obtained in high enantiopurity and found to be configurationally stable. Oligopeptide synthesis between the α-amino KATs and amino acid in dilute aqueous media was studied.

Ac oncise synthesis of acylborons was achieved by ozonolysis of alkenyl MIDA( N-methyliminodiacetic acid) boronates.T his reaction exhibits excellent functional-group tolerance and is applicable to various acyl MIDAb oronates and potassium acyltrifluroborates (KATs) which could not be synthesized by previous methods.I na ddition, a-amino acylborons,w hich would be essential for peptide ligations, were prepared for the first time.T he acylboron of l-alanine was obtained in high enantiopurity and found to be configurationally stable.O ligopeptide synthesis between the a-amino KATs and amino acid in dilute aqueous media was studied. Scheme 1. A) Previous approaches to the synthesis of acylborons. B) Acylboron synthesis by ozonolysis of alkenylM IDA boronate. Bt = benzotriazole, MIDA = N-methyliminodiacetic acid.

B 2 pin 2 (1.2 equiv) [Ir(OMe)(cod)] 2 / 1,10-phenanthroline (3-5 mol%) 2-norbornene (1.0 equiv)

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