81289-22-7

Upstream product

• 90-02-8 salicylaldehyde 
• 102-96-5 (2-nitroethenyl)benzene 
• 57543-84-7 2-phenyl-3-nitro-2H-chromene 
• 96853-36-0 β-(2-hydroxyphenyl)nitroethane 
• 100-52-7 benzaldehyde 

Downstream Products

• 81289-33-0 ((2R,3S)-2-Phenyl-chroman-3-yl)-(2-pyrrolidin-1-yl-ethyl)-amine 
• 81289-32-9 Benzyl-((2R,3S)-2-phenyl-chroman-3-yl)-amine 
• 112514-01-9 trans 3-amino-2-phenyl-3,4-dihydro-2H-<1>benzopyran 
• 577-85-5 3-hydroxyflavone 
• 81289-44-3 α-(o-hydroxybenzyl)-β-phenylethylamine 

Relevant academic research and scientific papers

Syntheses of 2-Benzylbenzofuran Derivatives and 2-Aryl-nitrochroman Derivatives from Nitroalkene Precursors

Simple and straightforward methods for the synthesis of 2-benzylbenzofuran, 3-substituted 2-benzylbenzofuran, and 2-aryl-nitrochroman derivatives are described. Benzofurans were generated from nitroalkenes by reduction with NaBH4 followed by a Nef reaction and acid-mediated cyclization, whereas 3-substituted 2-benzylbenzofurans were prepared from nitroalkenes by reactions with Grignard reagents followed by a Nef reaction and an acid-mediated cyclization in a one-pot process. The synthesis of chromans involved a Knoevenagel condensation and the 1,4-diazabicyclo[2.2.2]octane (DABCO) assisted cyclization of β-(2-hydroxyphenyl)-nitroethanes and benzaldehydes, also in a one-pot process. Simple and convenient methods for the synthesis of 2-benzylbenzofuran, 3-substituted 2-benzylbenzofuran, and 2-aryl-nitrochroman derivatives are described.

REACTION OF POTASSIUM SUPEROXIDE WITH 3-NITRO-2-PHENYL-2H-1-BENZOPYRANS AND THEIR DIHYDRO DERIVATIVES

3-Nitro-2-phenyl-2H-1-benzopyrans on treatment with potassium superoxide in dimethyl sulphoxide are degraded mainly to the corresponding salicylic acids and benzoic acids. Formation of flavonols, as a minor product are also observed. The dihydro derivatives of 3-nitro-2-phenyl-2H-1-benzopyrans are converted to the corresponding flavonols by potassium superoxide in benzene containing 18-crown-6 ether.

Sodium Borohydride Reduction of 3-Nitro-2-substituted-phenyl-2H-benzopyrans

Reaction of 3-nitro-2-substituted-phenyl-2H-benzopyrans (1-8) with NaBH4 at 5-10 deg C followed by reduction of the nitro group with hydrazine hydrate in the presence of Raney-nickel furnishes 3-amino-2-substituted-phenyl-3,4-dihydro-2H-benzopyrans