40016-10-2Relevant academic research and scientific papers
Synthesis of 1,3,4-oxadiazoles from 1,2-diacylhydrazines using [Et 2NSF2]BF4 as a practical cyclodehydration agent
Pouliot, Marie-France,Angers, Laetitia,Hamel, Jean-Denys,Paquin, Jean-Francois
supporting information; experimental part, p. 988 - 993 (2012/04/10)
The preparation of 1,3,4-oxadiazoles from 1,2-diacylhydrazines using XtalFluor-E ([Et2NSF2]BF4) as cyclodehydration reagent is described. Various functionalized 1,3,4-oxadiazoles were synthesized and it was found that the use of acetic acid as an additive generally improved the yields.
Rhodium(III)-catalyzed heterocycle synthesis using an internal oxidant: Improved reactivity and mechanistic studies
Guimond, Nicolas,Gorelsky, Serge I.,Fagnou, Keith
supporting information; experimental part, p. 6449 - 6457 (2011/06/16)
Directing groups that can act as internal oxidants have recently been shown to be beneficial in metal-catalyzed heterocycle syntheses that undergo C-H functionalization. Pursuant to the rhodium(III)-catalyzed redox-neutral isoquinolone synthesis that we recently reported, we present in this article the development of a more reactive internal oxidant/directing group that can promote the formation of a wide variety of isoquinolones at room temperature while employing low catalyst loadings (0.5 mol %). In contrast to previously reported oxidative rhodium(III)-catalyzed heterocycle syntheses, the new conditions allow for the first time the use of terminal alkynes. Also, it is shown that the use of alkenes, including ethylene, instead of alkynes leads to the room temperature formation of 3,4-dihydroisoquinolones. Mechanistic investigations of this new system point to a change in the turnover limiting step of the catalytic cycle relative to the previously reported conditions. Concerted metalation-deprotonation (CMD) is now proposed to be the turnover limiting step. In addition, DFT calculations conducted on this system agree with a stepwise C-N bond reductive elimination/N-O bond oxidative addition mechanism to afford the desired heterocycle. Concepts highlighted by the calculations were found to be consistent with experimental results.
4-Oxa and 4-thia steroids
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, (2008/06/13)
The compounds of the present invention are those of structural formula (I) STR1 wherein X is oxygen or sulfur. Pharmaceutical compositions and methods of use of the compounds in the treatment of hyperandrogenic conditions are disclosed. In addition, the combination of the compounds with other active agents such as finasteride, minoxidil and retinoic acid or a derivative thereof is disclosed.
