jo025924e_si_001.pdf (98.89 kB)
Efficient Entry to Highly Functionalized β-Lactams by Regio- and Stereoselective 1,3-Dipolar Cycloaddition Reaction of 2-Azetidinone-Tethered Nitrones. Synthetic Applications
journal contribution
posted on 2002-09-07, 00:00 authored by Benito Alcaide, Pedro Almendros, Jose M. Alonso, Moustafa F. Aly, Carmen Pardo, Elena Sáez, M. Rosario TorresRacemic as well as optically pure 2-azetidinone-tethered nitrones, both cyclic and acyclic, were
smoothly prepared from 4-oxoazetidine-2-carbaldehydes. The regio- and diastereoselectivities of
the intermolecular 1,3-dipolar cycloaddition reactions of 2-azetidinone-tethered nitrones with
substituted alkenes and alkynes were investigated. 2-Azetidinone-tethered nitrones on reacting
with various dipolarophiles yielded isoxazolinyl-, isoxazolidinyl-, or fused polycyclic-β-lactams,
exhibiting good regio- and facial stereoselectivity in the most of the cases. In addition, some
interesting transformations of these cycloadducts were performed, yielding aziridinyl β-lactams or
functionalized β-alkoxycarbonyl γ-lactams (derivatives of the aza analogue of paraconic acid).