Synthesis of Kaempferitrin

Link: JOC ASAP

Sameer Urgaonkar and Jared T. Shaw*

Chemical Biology Program, Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, Massachusetts 02142

This is a paper presenting a synthesis of this bisglycosilated molecule called Kaempferitrin:

The thing that caught my attention was the clever use of internal hydrogen-bonding to regioselectively putting protecting group on and taking protecting group off. For example, in the synthesis of 7, one of the ortho-OH group to the carbonyl did not react with MOMCl. And again in the transformation of 8 to 9, only the OH group ortho to the carbonyl was deprotected indicating the probable participation of that carbonyl.

And in the final step from 10 to 11, the Ts group was used strategically so that the di-deprotection of OMOM and OMe was possible without affecting the OTs group. I guess this last point is not as significant as the earlier protecting group manipulation steps.

Methylpentanediolborane: Easy Access to New Air- and Chromatography-Stable, Highly Functionalized Vinylboronates

Link: JOC ASAP

Nageswaran PraveenGanesh, Sylvain d’Hondt, and Pierre Yves Chavant*

Département de Chimie Moléculaire, CNRS, Université Joseph Fourier, BP-53, 38041 Grenoble Cedex 9, France  

As the title says, the paper detailed the synthesis of air and silica gel stable vinyl boronate. Several of these compounds were prepared as the scheme below suggests.

I guess one aspect of this paper that caught my attention was their way of making MPBH or 1 which I like:

And that is by using the diborane gas they made from NaBH4 and I2. In their experimental, they said the gas is pyrophoric and hydrogen was also generated, so extra care must be taken. For everything else, look up the paper.