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Volumn 47, Issue 41, 2006, Pages 7301-7306

The first total synthesis of (±)-annosqualine by means of oxidative enamide-phenol coupling: pronounced effect of phenoxide formation on the phenol oxidation mechanism

Author keywords

Annosqualine; Enamide phenol coupling; Iodobenzene diacetate; Phenoxide formation; Spiro isoquinoline alkaloid

Indexed keywords

1 METHYL 1,2,3,4 TETRAHYDROISOQUINOLINE DERIVATIVE; ANNOSQUALINE; ENAMINE; HYDROXYL GROUP; IODINE; ISOQUINOLINE DERIVATIVE; PHENOL; PHENOXIDE; TETRAHYDROISOQUINOLINE DERIVATIVE; UNCLASSIFIED DRUG;

EID: 33748331441     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tetlet.2006.08.028     Document Type: Article
Times cited : (54)

References (30)
  • 16
    • 0037126840 scopus 로고    scopus 로고
    • For recent outstanding reports on natural product synthesis by using hypervalent iodine reagents, see:
    • For recent outstanding reports on natural product synthesis by using hypervalent iodine reagents, see:. Tohma H., Harayama Y., Hashizume M., Iwata M., Egi M., and Kita Y. Angew. Chem., Int. Ed. 41 (2002) 348-350
    • (2002) Angew. Chem., Int. Ed. , vol.41 , pp. 348-350
    • Tohma, H.1    Harayama, Y.2    Hashizume, M.3    Iwata, M.4    Egi, M.5    Kita, Y.6
  • 20
    • 0027959746 scopus 로고
    • Potassium carbonate could also be used for the oxidation; however, the yield (up to 20%) was found to be much lower than that of the case of n-butyllithium. The reaction could be carried out in a homogeneous phase by the use of n-butyllithium. Similar aromatic oxidation of phenolic compounds with a hypervalent iodine reagent in the presence of sodium hydride was reported, although the reason for the formation of the corresponding phenoxides was not mentioned in the literature. See:
    • Potassium carbonate could also be used for the oxidation; however, the yield (up to 20%) was found to be much lower than that of the case of n-butyllithium. The reaction could be carried out in a homogeneous phase by the use of n-butyllithium. Similar aromatic oxidation of phenolic compounds with a hypervalent iodine reagent in the presence of sodium hydride was reported, although the reason for the formation of the corresponding phenoxides was not mentioned in the literature. See:. de Sousa J.D.F., Rodrigues J.A.R., and Abramovitch R.A. J. Am. Chem. Soc. 116 (1994) 9745-9746
    • (1994) J. Am. Chem. Soc. , vol.116 , pp. 9745-9746
    • de Sousa, J.D.F.1    Rodrigues, J.A.R.2    Abramovitch, R.A.3
  • 22
    • 33748308223 scopus 로고    scopus 로고
    • note
    • Treatment of n-BuLi with HFIP probably generated lithium hexafluoroisopropoxide, which on further treatment with 5 gave the corresponding phenoxide. These processes should be carried out at below 4 °C, due to the instability of the phenoxide. When these processes were conducted at room temperature, the starting 3,4-dihydroisoquinoline 3 was recovered as the degradation product.
  • 23
    • 33748327533 scopus 로고    scopus 로고
    • note
    • +): 325.1314; found 325.1323.
  • 26
    • 33748318641 scopus 로고    scopus 로고
    • note
    • Bromination of 1-benzyloxy-2,3-dimethoxybenzene under the same reaction conditions as described in Scheme 1 gave bromide 11 and its regioisomer 12 in a ratio of ca. 1:1.
  • 27
    • 33748312546 scopus 로고    scopus 로고
    • note
    • Formylation of 13 with n-BuLi and DMF gave the desired aldehyde in 40-60% yield, and the corresponding primary alcohol was isolated in 30-40% yield, although the mechanism for its formation still remains obscure.
  • 28
    • 33748303587 scopus 로고    scopus 로고
    • note
    • +): 382.1654; found 382.1672.
  • 30
    • 33748305027 scopus 로고    scopus 로고
    • note
    • +): 341.1263; found 341.1287.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.