Biomedical subjects
Publications and source records attributed to Lars Uehlin.
Aminoboranes have been shown to be highly efficient and mild iminium ion generators in the Mannich-type aminative coupling of aldehydes with silyl ketene acetals. By using aminoboranes bearing bulky amino groups, such as a diisopropylamino group, free secondary amines can be successfully used as the amino component in a three-component Mannich reaction with aldehydes and silyl ketene acetals.
Unlike ordinary boron enolates, such as dialkylboryl (R(2)B) and dialkoxyboryl ((RO)(2)B) derivatives, reactions of diaminoboryl ((R(2)N)(2)B) enolates with aldehydes proceed with the concurrent transfer of amino and enoxy groups from the boron to the aldehyde carbon, yielding beta-amino ketones in a selective manner.
New chiral diselenides were prepared in a few steps from readily available starting materials. The selenium electrophiles generated from these diselenides were used for the efficient stereoselective inter- and intramolecular functionalization of alkenes. The substitution pattern influences the stereoselectivities and protection of the hydroxy moiety in the chiral side chain led to increased selectivities and yields in the selenenylation reactions. An additional substituent in the second ortho position was advantageous as well. Addition products with up to 96% de were obtained. The influence of the nucleophile on the outcome of selenenylations of alkenes was studied to some extent as well.