Cyclizations of Aminyl Radicals Generated from Substoichiometric Stannane

Abstract

Substoichiometric amounts of tributyltin hydride were utilized in nitrogen-centered radical cyclizations onto silyl enol ethers for the formation of substituted cyclic imines.

aminyl radical cyclization - substoichiometric tributyltin hydride - silyl enol ethers - cyclic imines

References and Notes

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6

For an example of an elimination of tributyltin radical from a carbon-centered radical α to a tin-bound amine, see ref. 2b.

7

We did not explore addition rates slower than 0.2 mL/h as the reaction times became prohibitively long.

8 Benati L. Bencivenni G. Leardini R. Nanni D. Minozzi M. Spagnolo P. Scialpi R. Zanardi G. Org. Lett.  2006,  8:  2499 

9

While cyclization of azide 8 using 15 mol% of tributyltin hydride provided good conversion to the cyclized products, these conditions proved not to be robust for other substi-tution patterns. Cyclizations using 30 mol% tributyltin hydride proved to be general and reliable for all substrates examined.

10

We were also able to isolate 12% of the cis-isomer.

11 Marco JL. J. Heterocycl. Chem.  1986,  1059 

12 Arai T. Abe H. Aoyagi S. Kibayashi C. Tetrahedron Lett.  2004,  45:  5921