Iodocyclization of O-(3-cyclohexenyl)thiocarbamidates. An unexpected approach to vicinal cis-aminocyclohexenols

Journal of Organic Chemistry

Volumn 65, Issue 16, 2000, Pages 4826-4829

  Sabaté, Mar ^a,b   Llebaria, Amadeu ^b   Molins, Elies ^c   Miravitlles, Carles ^c   Delgado, Antonio ^a  

^a UNIVERSITY OF BARCELONA   (Spain)

^b Inst d'Investigations B   (Spain)

^c INSTITUT DE CIÈNCIA DE MATERIALS DE BARCELONA ICMAB CSIC   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

AMINOCYCLOHEXENOL; CYCLOHEXYLAMINE; O (3 CYCLOHEXENYL)THIOCARBAMIDATE; UNCLASSIFIED DRUG;

ARTICLE; CHEMICAL ANALYSIS; CIS TRANS ISOMERISM; CYCLIZATION; HYDROLYSIS; PROTON NUCLEAR MAGNETIC RESONANCE; SYNTHESIS; X RAY DIFFRACTION;

EID: 0034637495     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo991980c     Document Type: Article

References (18)

1. Amino alcohols 1 had already been prepared in our laboratory according to described procedures by a multistep synthesis in low overall yields (unpublished results).
2. (a) Knapp, S.; Patel, D. V. J. Am. Chem. Soc. 1983, 105, 6985-6986.
3. (b) Knapp, S.; Patel, D. V. J. Org. Chem. 1984, 49, 5072-5076.
4. Knapp, S. Chem. Soc. Rev. 1999, 61-72.
5. For examples of related 1,3-iodocyclizations in cyclohexene derivatives, see: (a) Carrol, F. I.; Abraham, P.; Pitner, J. B.; Jablonski, S. D.; Sing, P.; Kwon, Y. W.; Triggle, D. J. J. Chem. Soc., Chem. Commun. 1992, 795-796.
6. (b) Knapp, S.; Lal, G. S.; Sahai, D. J. Org. Chem. 1986, 51, 380-383.
7. Iodocyclization of 2b with N-iodosuccinimide afforded diiodide 7b in low yield together with other unidentified byproducts.
8. Compounds 7a-c showed very similar spectral patterns. Structural assignment of thiocarbamates 7a-c by direct inspection of their NMR data was not possible due to extensive peak broadening as a result, in part, of the rotameric equilibrium associated with the thiocarbamate moiety.
9. Iminium salts have been proposed as intermediates in related halocyclization processes. See, for example, ref 2a and: (a) Knapp, S.; Patel, D. V. Tetrahedron Lett. 1982, 23, 3539;
10. (b) Winstein, S.; Goodman, L.; Boschan, S. J. Am. Chem. Soc. 1950, 72, 2311.
11. 5-I bond (7a-c numbering, see Scheme 3).
12. Since no epimerization of starting dioidides 7a-c was observed, direct equilibration between 7a-c and the iminium salt B′ can be ruled out (see Scheme 3).
13. The identity of the reaction products was confirmed as follows: (a) dehydroiodination of iodocarbamates 8b,c afforded the corresponding tetrahydrobenzoxazolones 6b,c and 9b,c (see text);
14. (b) the structure of iodocarbamates 3b,c was secured by X-ray diffraction analysis of 3c;
15. carbamates 6a-c were obtained independently from thiocarbamidates 4a-c via the iodocyclization-dehydrohalogenation sequence outlined in Scheme 1 (ref 2b);
16. the structure of carbamates 9a-c was inferred from spectroscopic data and by their conversion into amino alcohols 11a-c (Scheme 7).
17. Formation of C + D from A could be explained by analogy to the postulated mechanism for the formation of 6 + 9 from 3 (see text and Scheme 5).
18. Gogek, C. J.; Moir, R. Y.; Purves, C. B. Can. J. Chem. 1951, 29, 946-948.