Hexacarbonyidicobalt-alkyne complexes as convenient Co2(Co)8 surrogates in the catalytic Pauson-Khand reaction

Tetrahedron Letters

Volumn 39, Issue 42, 1998, Pages 7641-7644

  Belanger, David B ^a   Livinghouse, Tom ^a  

^a MONTANA STATE UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ARTICLE; CATALYSIS; CYCLIZATION; MOLECULAR INTERACTION; STRUCTURE ANALYSIS; SYNTHESIS;

EID: 0032532236     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(98)01694-3     Document Type: Article

References (9)

1. 1. Recipient of a Japan Society for the Promotion of Science Fellowship, 1997.
2. 2. Hosokawa, S.; Isobe, M. Tetrahedron Lett. 1998, 39, 2609-2612.
3. 3SiH.
4. 8 (1.8 g, 5.3 mmol, 1.00 equiv) in diethyl ether (25 mL) under argon was added 2-methyl-3-butyn-2-ol (485 μL, 5.0 mmol, 0.95 equiv) dropwise. The resulting solution was allowed to stir for 5 h at rt, then the solvent was removed under reduced pressure. Flash chromatography using a 5 × 9 cm silica gel column (100% hexanes for nonpolar material elution, then 15% EtOAc/hexanes for product elution) and subsequent evaporation of solvent afforded 1.57 g (85%) of complex 1a as a deep red microcrystalline solid.
5. 5. Sugihara has shown that selected primary amines induce a rate enhancement of the stoichiometric PKR. Sugihara, T.; Yamada, M.; Ban, H.; Yamaguchi, M.; Kaneko, C. Angew. Chem. Int. Ed. Engl. 1997, 36, 2801-2804.
6. 2, 15% ethyl acetate in hexanes to 30% ethyl acetate in hexanes gradient for elution) afforded 125 mg of 5-oxo-3,3a,4,5-tetrahydro-1H - pentalene-2,2-dicarboxylic acid diethyl ester 2b (93% yield) as a colorless oil.
7. 7. (a) Conducted at 65 °C.
8. (b) Conducted at 70 °C.
9. 8. A sample of 1a that was deliberately exposed to air at room temperature for 24 h showed no loss of activity as a precatalyst.