TY - JOUR
T1 - Synthesis of new polycyclic oxazol-2-one derivatives by a tandem [4 + 2] cycloaddition/cyclopentannulation/1,5-sigmatropic rearrangement process of fischer (arylalkynyl)(alkoxy)carbenes and exo-2-oxazolidinone dienes
AU - Reyes, Leonor
AU - Mendoza, Humberto
AU - Vázquez, Miguel Angel
AU - Ortega-Jiménez, Fernando
AU - Fuentes-Benítes, Aydeé
AU - Flores-Conde, María Inés
AU - Jiménez-Vázquez, Hugo
AU - Miranda, René
AU - Tamariz, Joaquín
AU - Delgado, Francisco
PY - 2008/9/8
Y1 - 2008/9/8
N2 - An efficient and simple synthesis of highly substituted 9-ethoxy-3-phenyl-3H-fluorene[3,2-d]oxazol2-(4H,9H,10H)-one derivatives 10a-f by a tandem [4 + 2] cycloaddition/cyclopentannulation process of Fischer (arylethynyl)(ethoxy)carbene complexes (CO)5M=C(C≡CC 6H4-R)OCH2CH3 (1a, M = Cr, R = H; 1b, M = Cr, R = p-CH3; 1c, M = Cr, R = p-OCH3; 1d, M = W, R = H; 1e, M = W, R = p-CH3; If, M = W, R = p-OCH3) with exo-2-oxazolidinone dienes 7a-d is described. A study of reactivity as well as regio- and stereoselectivity in a tandem process of the Fischer carbene complexes 1 with the exo-heterocyclic dienes 7 was carried out. The cycloadditions were found to be highly regioselective, favoring the para cycloadducts, and highly stereoselective, giving the trans diastereoisomers. The stereochemical assignment of the cycloadducts was supported by NOE measurements, and the derivatives 10b,c,e were further characterized by single crystal X-ray diffraction. A rationalization of the regioselectivity was carried out through an FMO analysis of the energies and coefficients for the most stable conformations of carbenes la,d and for diene 7a, showing a stronger interaction for the observed para cycloadduct than for the meta regioisomer. The aromatization of cycloadducts 10a-f with HCl and DDQ is also reported.
AB - An efficient and simple synthesis of highly substituted 9-ethoxy-3-phenyl-3H-fluorene[3,2-d]oxazol2-(4H,9H,10H)-one derivatives 10a-f by a tandem [4 + 2] cycloaddition/cyclopentannulation process of Fischer (arylethynyl)(ethoxy)carbene complexes (CO)5M=C(C≡CC 6H4-R)OCH2CH3 (1a, M = Cr, R = H; 1b, M = Cr, R = p-CH3; 1c, M = Cr, R = p-OCH3; 1d, M = W, R = H; 1e, M = W, R = p-CH3; If, M = W, R = p-OCH3) with exo-2-oxazolidinone dienes 7a-d is described. A study of reactivity as well as regio- and stereoselectivity in a tandem process of the Fischer carbene complexes 1 with the exo-heterocyclic dienes 7 was carried out. The cycloadditions were found to be highly regioselective, favoring the para cycloadducts, and highly stereoselective, giving the trans diastereoisomers. The stereochemical assignment of the cycloadducts was supported by NOE measurements, and the derivatives 10b,c,e were further characterized by single crystal X-ray diffraction. A rationalization of the regioselectivity was carried out through an FMO analysis of the energies and coefficients for the most stable conformations of carbenes la,d and for diene 7a, showing a stronger interaction for the observed para cycloadduct than for the meta regioisomer. The aromatization of cycloadducts 10a-f with HCl and DDQ is also reported.
UR - http://www.scopus.com/inward/record.url?scp=52649162365&partnerID=8YFLogxK
U2 - 10.1021/om8002416
DO - 10.1021/om8002416
M3 - Artículo
SN - 0276-7333
VL - 27
SP - 4334
EP - 4345
JO - Organometallics
JF - Organometallics
IS - 17
ER -