10.1021/jo202183u.s001
Heather
K. Lenker
Heather
K.
Lenker
Marcia E. Richard
Marcia E.
Richard
Kyle P. Reese
Kyle P.
Reese
Anthony F. Carter
Anthony F.
Carter
Jason D. Zawisky
Jason D.
Zawisky
Eric F. Winter
Eric F.
Winter
Timothy W. Bergeron
Timothy W.
Bergeron
Krysta S. Guydon
Krysta S.
Guydon
Robert A. Stockland
Robert A.
Stockland
Phospha-Michael Additions
to Activated
Internal Alkenes: Steric and Electronic Effects
American Chemical Society
2012
latter alkenes
ditolylphosphinic acid
Electronic EffectsThe addition
ethyl cinnamate
microwave reactor
addition reaction
ditolylphosphine oxide
substrate
phosphine oxide
Activated Internal Alkenes
methyl crotonate
room temperature
2012-02-03 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Phospha_Michael_Additions_to_Activated_Internal_Alkenes_Steric_and_Electronic_Effects/2553469
The addition of P(O)–H bonds to internal alkenes
has been
accomplished under solvent-free conditions without the addition of
a catalyst or radical initiator. Using a prototypical secondary phosphine
oxide, a range of substrates including cinnamates, crotonates, coumarins,
sulfones, and chalcones were successfully functionalized. Highly activated
acceptors such as isopropylidenemalononitrile and ethyl 2-cyano-3-methyl-2-butenoate
underwent the phospha-Michael reaction upon simple trituration of
the reagents at room temperature, whereas less activated substrates
such as ethyl cinnamate and methyl crotonate required heating (>150
°C) in a microwave reactor to achieve significant consumption
of the starting alkenes. For the latter alkenes, a competing reaction
involving disproportionation of the ditolylphosphine oxide into ditolylphosphinic
acid and ditolylphosphine was observed at the high temperatures needed
to promote the addition reaction.