1,4-Naphthalenedione, 2-bromo- (9CI) → HCID 10399257, compound

HRID 260755Notes

Reaction equation

HRID 260755 reaction equation
[CH:1]1[CH:2]=[CH:3][C:4]2[C:17](=[O:18])[C:16]3[C:8]4[C:9]([CH:13]=[CH:14][N:15]=3)=[CH:10][CH:11]=N[C:7]=4[C:5]=2[CH:6]=1.C[O:20]C1C=NC2C3C=CC=CC=3C(C3C=2C=1C=CN=3)=O.CC1C2=C3C(=NC=C2)C(=O)C2C(=CC=CC=2)C3=NC=1.BrC1C(=O)C2C(C(=O)C=1)=CC=CC=2.CN(C)N=C/C=C/COC.CN(C)N=C/C=C/CC>>[CH3:11][CH2:10][C:9]1[CH:13]=[CH:14][N:15]=[C:16]2[C:17]([C:4]3[C:5]([C:7](=[O:20])[C:8]=12)=[CH:6][CH:1]=[CH:2][CH:3]=3)=[O:18]

Participants

7

Reactant 6

HCID 749441,4-Naphthalenedione, 2-bromo- (9CI)HCID 1226833-MethoxysampangineHCID 3871957H-Naphtho(1,2,3-ij)(2,7)naphthyridin-7-oneHCID 98377513-MethylsampangineHCID 86747024trans-2-Pentenal N,N-DimethylhydrazoneHCID 86747025HCID 86747025, compound

Product 1

HCID 10399257HCID 10399257, compound

Procedure

It was unexpectedly discovered that a modification of the foregoing method for preparing sampangine enabled the preparation of 3-methoxysampangine (19) and 3-methylsampangine (14) heretofore never achieved. The Hetero Diels-Alder reaction of 2-bromo-1,4-naphthoquinone (1) with (E)-4-methoxy-2-butenal N,N-dimethylhydrazone (17) or (E)-2-pentenal N,N-dimethylhydrazone (12) gave 4'-methoxycleistopholine (18) or homocleistopholine (13), respectively, in modest yield. Generation of the sampanglue nucleus (i.e., 3-methoxysampangine (19)and 3-methylsampangine (14)) was accomplished through condensation of the corresponding cleistopholine with dimethylformamide dimethylacetal. For the 3-methylsampangine reaction, at least two additional compounds, 4'-oxohomocleistopholine (15) and dimer 16, were produced in significant quantities. The exact yields for 15 and 16 remain undetermined due to difficulty in isolation. Chromatography of the reaction product gave fractions consisting of recovered homocleistopholine (11%), 3-methylsampangine (6%), and a fraction consisting of compounds 14-16. Recrystallization of the latter fraction from ethyl acetate followed by manual separation of the crystal types gave pure 15 and 16; 3-methylsampangine crystallized as long yellow needles, 4'-oxohomocleistophiline (6%, 15) as nearly perfect golden octahedra, and dimer 16 (6%) as rectangular yellow plates. ##STR3##

Sources & evidence

ORD record
ord-83c8905bcc0748c4add11a30632a5dda
Source dataset
uspto-grants-1996_06
Patent number
US05530004

Reaction notes

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