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Volumn 68, Issue 17, 2003, Pages 6522-6534

The role of steric and electronic interactions in the stereocontrol of the asymmetric 1,3-dipolar reactions of 5-ethoxy-3-p-(S)-tolylsulfinylfuran-2(5H)-ones with diazoalkanes: Theoretical calculations and experimental evidences

Author keywords

[No Author keywords available]

Indexed keywords

COMPUTATIONAL METHODS; HYDROGEN BONDS; REACTION KINETICS; SOLVENTS;

EID: 0042009346     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo0345603     Document Type: Article
Times cited : (49)

References (47)
  • 14
    • 0043025740 scopus 로고    scopus 로고
    • note
    • The terminology syn/anti indicates the spatial arrangement of the alkoxy group at C-5 and the pyrazoline ring at the furanone moiety. It also indicates that the approach of the dipole has taken place either to the face containing the alkoxy group (syn-approach) or to the opposite one (anti-approach). Therefore, the syn/anti ratio will be indicative of the π-facial selectivity of the reaction. The term exo indicates the trans arrangement of the methyl group of the diazoethane with respect to the furanone moiety at the pyrazoline ring. It is characteristic of the exo approach of the dipole to the dipolarophile, using as the reference the carbonyl group at the later.
  • 15
    • 0041522945 scopus 로고    scopus 로고
    • note
    • As the isolation of 1b in its diastereomerically pure form was very difficult these reactions were performed starting from a 94:6 mixture of 1b and 1a. As a consequence, in all cases we also obtained small amounts (∼6%) of the adduct syn-4a-exo, which could be easily separable from the 4b adducts.
  • 16
    • 0042524784 scopus 로고    scopus 로고
    • note
    • The data corresponding to this reaction in ref 3 indicate that anti-5b was exclusively formed under the conditions indicated in entry 6. However, taking into account that compound syn-4b-exo resulted from the approach of the diazoethane to the face of the dipolarophile bearing the OEt group at C-5, the absence of a similar adduct (syn-5b) in the reaction of 1b with the less hindered diazomethane was difficult to explain. Therefore, we have repeated the later reaction and thoroughly studied the reaction crude, with the results indicated in entry 6 of Table 2. This mistake was responsible for the wrong conclusions reported in ref 3,
  • 17
    • 0042023916 scopus 로고    scopus 로고
    • note
    • This contrasts with the previously reported proposal in ref 3, which assumed that the π-facial selectivity was exclusively controlled by the sulfinyl configuration through the steric effects present in the most stable conformation around the C-S bond.
  • 18
    • 0043025716 scopus 로고    scopus 로고
    • note
    • Taking into account that the carbonated end at the dipole supports a negative charge, initially we thought that the alkoxy oxygen could exhibit a possitive charge as a consequence of the strong anomeric effect present in 5-alkoxy-furan-2-(5H)-ones, but further theoretical calculations revealed that this was not the case.
  • 21
    • 0041522913 scopus 로고    scopus 로고
    • note
    • These data suggest that the results published in ref 16, concerning the π-facial selectivity of the reaction of 5-methoxy-2(5H)-furanone with diazomethane at -10 °C (30:70 syn:anti), could be wrong. On the other hand, the stereoselectivity reported in ref 17 for reactions of 5-(l)-menthyloxy-2(5H)-furanone with diazomethane (40: 60 syn:anti) is not consistent with that of ref 16 from a steric point of view (as the menthyloxy group is bulkier than the methoxy one, a higher proportion of the anti-adduct must be expected in the former case).
  • 23
    • 33845277897 scopus 로고
    • The steric differentiation of the diastereotopic faces at the furanone ring produced by the OMe group at C-5 was able to control the π-facial selectivity of their reactions with cyclopentadiene (Feringa, B. L.; de Jong, J. C. J. Org. Chem. 1988, 53, 1125-1127).
    • (1988) J. Org. Chem. , vol.53 , pp. 1125-1127
    • Feringa, B.L.1    De Jong, J.C.2
  • 39
    • 0001557536 scopus 로고
    • New York; Collect
    • Arndt, F. Organic Syntheses; Wiley: New York, 1941; Collect. Vol. II, pp 165-167.
    • (1941) Organic Syntheses , vol.2 , pp. 165-167
    • Arndt, F.1


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.