Mechanistic studies on the O-directed free-radical hydrostannation of disubstituted acetylenes with Ph3SnH and Et3B and on the iodination of allylically oxygenated alpha-triphenylstannylalkenes.
[reaction: see text] The free-radical hydrostannation of 1 with Ph(3)SnH and catalytic Et(3)B in PhMe has been mechanistically probed. At high Ph(3)SnH concentrations, the O-directed hydrostannation pathway dominates, and 2 is formed with good selectivity (ca. 11.1:1). Substantially lower stannane/substrate concentrations increase the amount of tandem 5-exo-trig cyclization product 3 that is observed.
Dimopoulos
Paschalis
P
The Christopher Ingold Laboratories, The Chemistry Department, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom.
George
Jonathan
J
Tocher
Derek A
DA
Manaviazar
Soraya
S
Hale
Karl J
KJ