Carbolithiation of ene-carbamates. Application to the synthesis of 2,3-disubstituted ene-carbamates

Tetrahedron Letters

Volumn 45, Issue 3, 2004, Pages 483-484

  Lepifre, Franck ^a   Cottineau, Bertrand ^a   Mousset, Deborah ^a   Bouyssou, Pascal ^a   Coudert, Gerard ^a  

^a UNIVERSITÉ D'ORLÉANS   (France)

Author keywords

Carbolithiation; Ene carbamates

Indexed keywords

CARBAMIC ACID DERIVATIVE;

ARTICLE; BROMINATION; CARBOLITHIATION; CHEMICAL REACTION; CHROMATOGRAPHY; ELIMINATION REACTION; STEREOCHEMISTRY; TEMPERATURE;

EID: 0345732578     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tetlet.2003.11.012     Document Type: Article

References (10)

1. Lepifre F., Buon C., Rabot R., Bouyssou P., Coudert G. Tetrahedron Lett. 40:1999;6373-6376 Lepifre F., Buon C., Bouyssou P., Coudert G. Heterocycl. Commun. 6:2000;397-402 Buon C., Chacun-Lefevre L., Rabot R., Bouyssou P., Coudert G. Tetrahedron. 56:2000;605-614.
2. Lepifre F., Buon C., Rabot R., Bouyssou P., Coudert G. Tetrahedron Lett. 40:1999;6373-6376 Lepifre F., Buon C., Bouyssou P., Coudert G. Heterocycl. Commun. 6:2000;397-402 Buon C., Chacun-Lefevre L., Rabot R., Bouyssou P., Coudert G. Tetrahedron. 56:2000;605-614.
3. Lepifre F., Buon C., Rabot R., Bouyssou P., Coudert G. Tetrahedron Lett. 40:1999;6373-6376 Lepifre F., Buon C., Bouyssou P., Coudert G. Heterocycl. Commun. 6:2000;397-402 Buon C., Chacun-Lefevre L., Rabot R., Bouyssou P., Coudert G. Tetrahedron. 56:2000;605-614.
4. Lepifre F., Clavier S., Bouyssou P., Coudert G. Tetrahedron. 57:2001;6969-6975.
5. Ziegler K., Bähr K. Chem. Ber. 61:1928;253-263.
6. Knochel P. Trost B., Fleming I. Comprehensive Organic Synthesis. 4:1991;865-872 Pergamon, New York.
7. Review: Marek I. J. Chem. Soc., Perkin Trans 1. 1999;535-544.
8. Synthesis of compounds 3a-e , general procedure. To a solution of 1 in anhydrous THF (0.1 M) previously cooled to -78°C, RLi (equiv: see Table 1) was added slowly at -78°C. The resulting solution was stirred at 0°C for 30 min. After hydrolysis, the aqueous layer was extracted with ethyl acetate. The organic layer was dried over magnesium sulfate, filtered and evaporated. The mixture of inseparable diastereoisomers 3 was purified by flash chromatography on silica gel (PE/EtOAc: 9/1). Compounds were obtained with an unoptimized diastereoisomeric excess near 10%.
9. Formation of compounds 5a-d , general procedure. To a solution of 1 in anhydrous THF (0.1 M) previously cooled to -78°C, RLi (equiv: see Table 2) was added slowly at -78°C. The resulting solution was stirred at 0°C for 30 min. The mixture was then cooled to -78°C, and treated with 1,2-dibromotetrachloroethane (equiv: see Table 2). The solution was stirred at -78°C for 15 min. After hydrolysis, the aqueous layer was extracted with ethyl acetate. The organic layer was dried over magnesium sulfate, filtered and evaporated. The product was purified by flash chromatography on silica gel (PE/EtOAc: 9/1).
10. 3) δ 23.02, 27.96, 29.02, 36.54, 48.70, 74.76, 126.59, 122.34, 128.11, 129.03, 129.62, 136.07, 139.36, 142.48, 154.33.