Development of a tandem cyclization mediated by samarium(II) iodide: sequential intramolecular conjugate addition/nucleophilic acyl substitution

Tetrahedron Letters

Volumn 47, Issue 35, 2006, Pages 6225-6227

  St Jean Jr , David J ^a   Cheng, Edward P ^a   Bercot, Eric A ^a  

^a AMGEN INC   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ACETAL DERIVATIVE; ANION; REAGENT; SAMARIUM DIIODIDE; TRICYCLIC AROMATIC COMPOUND;

ADDITION REACTION; ARTICLE; CHEMICAL REACTION; CHEMICAL STRUCTURE; CONJUGATION; CYCLIZATION; STEREOCHEMISTRY; SUBSTITUTION REACTION; X RAY CRYSTALLOGRAPHY;

EID: 33746296220     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tetlet.2006.06.146     Document Type: Article

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20. The reaction was followed by TLC. Once the conjugate addition was complete, the mixture was irradiated with visible light for 12 h. This resulted in a complex mixture of nonpolar products.
21. These substrates were synthesized from 1,7-dichloroheptan-4-one based on procedures that were reported previously (see Ref. 12).
22. 2 (0.050 g, 0.16 mmol) was added under a stream of nitrogen. A solution of 5 (0.434 g, 1.0 mmol) and MeOH (0.041 mL, 1.0 mmol) in 10 mL of THF was then added dropwise. The solution was slowly allowed to warm to -20 °C (over 5 h) and was then maintained at that temperature for 2.5 d. After that time, the blue solution was quenched with 25 mL of a saturated aqueous solution of Rochelle's salt. After stirring for 3 h at rt, the mixture was extracted with EtOAc. The combined extracts were dried and concentrated to provide an oil, which was purified by column chromatography (12.5-40% EA/Hex) to yield 0.122 g of 2 (67%) as oil that slowly crystallized.