Catalyst- and solvent-free conditions as an environmentally benign approach to 4-aryl-3-cyano-hexahydro-4H-1,2-benzoxazine-2-oxides

Abstract

Experimental procedure for the [4 + 2] cycloaddition of 1b with 2b(E)-1-Cyano-2-phenyl-1-nitroethene (1b) (0.511 g, 3.0 mmol) was charged in a two-necked round bottom flask equipped with a

Nitroacetonitrile and Its Synthetic Equivalents

“…Nitroalkenes are known to exhibit dual behavior in the Diels–Alder reaction: as a dienophile and as a heterodiene. − Cyanated nitroalkene 8 is also usable as an electron-deficient heterodiene, affording oxazine framework 15 in the reaction with electron-rich dienophile 14 (Scheme ). , Fused oxazine derivative 18 is obtained when O -allylated salicylaldehyde 16 is condensed with NAN, whereby intermediate 17 undergoes an intramolecular hetero-Diels–Alder reaction (Scheme ). …”

“…44−46 Cyanated nitroalkene 8 is also usable as an electron-deficient heterodiene, affording oxazine framework 15 in the reaction with electron-rich dienophile 14 (Scheme 6). 47,48 Fused oxazine derivative 18 is obtained when Oallylated salicylaldehyde 16 is condensed with NAN, whereby intermediate 17 undergoes an intramolecular hetero-Diels− Alder reaction (Scheme 7). 38 The resonance effect of nitro and cyano groups considerably decreases the electron density at the β-position in 8 to bias the electron density on the C−C double bond.…”

Chemistry of 2-aryl-1-cyano-1-nitroethenes. Part II. Chemical transformations

“…Aromatization of (39a-n) was achieved by reaction with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in the presence of O 2 . Biphenyls (40a-n) were isolated in 45-80% yield (Table 10 Vaccaro et al [22] presented an uncatalysed and solvent-free cycloaddition of ACNs (1, 12a-e, 16b, 32, 37b, 37d, 41a,b) to 1-(trimethylsilyloxy)-cyclohex-1-ene (42). The hexahydro-4H-1,2-benzoxazine-2-oxide (43a-l) formed was isolated with 80-90% yield (Table 11).…”

Aryl(hetaryl)-containing gem-cyanonitroethenes: Synthesis, structure, and reactions with 2,3-dimethyl-1,3-butadiene

“…Their reactions with 1,3-dipoles [7,[38][39][40][41][42] and vinyl ethers [43][44][45] yielding practically important cyclic compounds are of the particular interest.…”