Abstract
Di- and trisubstituted nitroalkenes tethered to dipolarophiles (unsaturated esters, nitriles) undergo tandem [4 + 2]/[3 + 2] cycloadditions with 2,3-dimethyl-2-butene or butyl vinyl ether in the presence of Lewis acids. For the dimethylene tether 1, the tandem cycloadduct 4 is the direct reaction product. The E configuration of the dipolarophile is preferred, and the products arise selectively from a syn-endo pathway. For a trimethylene-tethered precursors 2 the initial [4 + 2] cycloadducts 9 are isolable and undergo the second [3 + 2]-dipolar cycloaddition upon brief warming via a syn-exo pathway. The resulting nitroso acetals (4bB/B’ and llaB/B’) are cleaved with hydrogen and Raney nickel to afford the tricyclic lactams 12 and 14 stereoselectively in good yield.
Original language | English (US) |
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Pages (from-to) | 311-315 |
Number of pages | 5 |
Journal | Journal of the American Chemical Society |
Volume | 112 |
Issue number | 1 |
DOIs | |
State | Published - 1990 |
ASJC Scopus subject areas
- Catalysis
- General Chemistry
- Biochemistry
- Colloid and Surface Chemistry