First allylboration of organic compounds with the NN double bond. Synthesis of N-allylpyrazolidines and allyl-1,2-diphenylhydrazine

Triallylborane adds to the NN double bond of pyrazolines 1 and 2 at 0 °C giving after deboronation the corresponding N-allylpyrazolidines 4 and 5. Further transformations of allylpyrazolidine 4 including the cyclopropane ring opening were studied. Allylboration of azobenzene with triallylborane gives rise to 1-allyl-1,2-diphenylhydrazine.

Graphical abstractThe first example of addition of organoboron compound to NN double bound was found. It turned out that triallylborane easily adds to the NN bond of substituted pyrazolines and azobenzene gives rise to N-allylpyrazolidines and 1-allyl-1,2-diphenylhydrazine respectively. Reaction protocol is very easy and the yields are high.Figure optionsDownload full-size imageDownload as PowerPoint slide