An Improved Synthesis of Conjugated Nitroolefins

Useful Extensions of the Henry Reaction: Expeditious Routes to Nitroalkanes and Nitroalkenes in Aqueous Media

“…These generally involve the prior activation of the hydroxyl group followed by a base-induced elimination process. Reagents employed include MsCl-Et 3 N [10b,11] , Ac 2 O-AcONa [12] , Ph 3 P-CCl 4 -Et 3 N [13] , , catalytic piperidinemolecular sieves [15] , DCC [16] , phthalic anhydride [17] , P 2 O 5 [18] , Al 2 O 3 [19] , pivaloyl chloride [20] , SmI 2 [21] , etc. Recently, heterogeneous catalysts such as functionalized silica [22] , zeolite [23] and MCM-41 [24] have been reported to effect the dehydration of 2-nitroalcohols to nitroalkenes.…”

Diastereoselective Access to 3-Nitro-4-vinylidenetetrahydrofurans and 3-Nitro-4-vinylidenetetrahydropyrans and Their Conversion into 3,6-Dihydro-1,2-oxazines by Reverse Cope Elimination of Hydroxylamine Precursors

“…Acyclic nitroalkene 1f resulted from dehydration with basic alumina in CH 2 Cl 2 28 while isolation of 1e and 1g first required formation of mesylates, which subsequently underwent Et 3 N‐promoted elimination 29. The stereochemistries of the nitroalkenes were assigned on the basis of 1 H NMR spectra, by comparison with reported data 30…”

Morpholine Adsorbed on Silica Gel: A Novel and Mild Basic Catalyst for the Synthesis of α,β-Unsaturated Nitroalkenes

“…The (E)-geometry of the newly formed double bond was readily assigned on the basis of 1 H NMR spectra, the vinyl proton of the (E)-isomer appearing at lower ®eld than the corresponding proton of the (Z)-isomer because of the strong anisotropic effect of the nitro group [15]. 13 C NMR spectra of the products indicated that no contamination with (Z)-isomers occurred [14±15].…”