Acetic Anhydride → HCID 9437072, compound

HRID 2260478Notes

Reaction equation

HRID 2260478 reaction equation
[N+:1]([CH2:4][C:5]([C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1)=[O:6])([O-:3])=[O:2].CC(O[C:17]([CH3:19])=O)=O>CCOCC>[CH:7]1[CH:8]=[CH:9][C:17](/[CH:19]=[C:4](/[N+:1]([O-:3])=[O:2])\[C:5]([C:7]2[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=2)=[O:6])=[CH:4][CH:5]=1

Participants

4

Reactant 2

HCID 7918Acetic AnhydrideHCID 948332-Nitro-1-phenylethanone2×

Product 1

HCID 9437072HCID 9437072, compound

Reagents, catalysts & solvents 1

HCID 3283Diethyl EtherSolvent

Procedure

Condensation of α-nitroacetophenone (Compound 6) with N-methyl benzylidene imine (Compound 7) under the conditions detailed by Dornow et al., Ann., 588:40 (1954) (1.1 equiv. Ac2O, Et2O, reflux, 3 hours, 88 percent) provided (E)α-nitrochalcone (Compound 8) as the exclusive olefin isomer detected in the reaction mixture (Scheme 3). Treatment of Compound 8 with freshly cracked cyclopentadiene (9.0 equiv. 45° C., CH2Cl2 24 hours, 81 percent) provided a single predominant Diels-Alder adduct, Compound 9, derived from a [4+2] cycloaddition reaction through a transition state with the nitro substituent endo to the diene. Less than 1-3 percent of the diastereomeric exo adduct was detected. Notably, this Diels-Alder reaction proceeds almost exclusively to provide the sterically less favored adduct, Compound 9, presumably a consequence of a strong endo directing effect of the polarized nitro substituent. Use of cyclohexadiene in the place of cyclopentadiene provides the corresponding bicyclo[2.2.21]octane derivative.

Sources & evidence

ORD record
ord-9c3ba0852d344d248ad6a859747208d5
Source dataset
uspto-grants-1995_12
Patent number
US05478728

Reaction notes

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