303155-00-2Relevant academic research and scientific papers
Rhodium generated carbonyl ylides with p-quinones: Synthesis of oxa-bridged polycyclic systems
Muthusamy, Sengodagounder,Babu, Srinivasarao Arulananda,Gunanathan, Chidambaram,Suresh, Eringathodi,Dastidar, Parthasarathi,Jasra, Raksh Vir
, p. 7009 - 7019 (2001)
A series of α-diazo carbonyl compounds tethered to substituted cyclopentanone and cyclohexanone units with different tether lengths have been synthesized using diazomethane solution or methanesulphonyl azide. The above synthesized α-diazo carbonyl compounds with rhodium(II) acetate dimer furnish cyclic five- or six-membered-ring carbonyl ylide dipoles, which undergo facile 1,3-dipolar cycloaddition with p-quinones to furnish various novel oxa-bridged polycyclic systems 10, 13 and 11, 14 as C=C and C=O addition products of p-quinones. Very interesting unusual cyclization product, tri-oxapolycyclic compounds 12 and 15 were also obtained. Single-crystal X-ray analyses of 11a, 12d and 14a are reported to firmly establish the structure and stereochemistry of the oxa-bridged polycyclic systems. The molecules 11a and 14a exhibit novel C-H···O hydrogen bonding motif in the crystal structure. On the other hand, the molecule 12d revealed both O-H···O and C-H···O motifs in the solid-state architecture.
Tandem cyclization-cycloaddition behavior of rhodium carbenoids with carbonyl compounds: stereoselective studies on the construction of novel epoxy-bridged tetrahydropyranone frameworks.
Muthusamy, Sengodagounder,Babu, Srinivasarao Arulananda,Gunanathan, Chidambaram,Ganguly, Bishwajit,Suresh, Eringathodi,Dastidar, Parthasarathi
, p. 8019 - 8033 (2007/10/03)
Investigations and stereoselective studies on the tandem reactions of carbonyl ylides generated from alpha-diazo ketones in the presence of carbonyl compounds are presented in this paper. Intramolecular cyclization of rhodium carbenoids generated the transient five- or six-membered-ring carbonyl ylide dipoles, which efficiently underwent 1,3-dipolar cycloaddition reactions with various dipolarophiles such as aromatic aldehydes 15, alpha,beta-unsaturated aldehydes 18/24, alpha,beta-unsaturated ketones 27/28/31, and dienone 34. The transient carbonyl ylides underwent cycloadditions with various aromatic aldehydes to furnish diverse epoxy-bridged tetrahydropyranone ring systems in a diastereoselective manner. The cycloaddition of carbonyl ylides with alpha,beta-unsaturated aldehydes 18/24 or dienone 34 afforded C=O addition products in a chemoselective manner despite the presence of C=C bonds in the above dipolarophiles. Alternatively, the cycloaddition of carbonyl ylides with alpha,beta-unsaturated ketones 27/28 provided both the C=O and C=C cycloaddition products. The cycloaddition of carbonyl ylides with carbonyl compounds occurred in good yields and was found to be highly regio- and stereoselective. Single-crystal X-ray analyses were performed to unambiguously establish the structure and stereochemistry of the novel epoxy-bridged tetrahydropyranone ring systems 35a/38. Compound 35a exhibited both intermolecular C-H...O and intramolecular C-H...pi interaction motifs in the solid-state architecture. The regio-, chemo-, and stereoselectivity observed in these reactions have been investigated by semiempirical AM1 MO calculations. FMO analyses and transition state calculations have been performed for the cycloaddition of carbonyl ylides with alpha,beta-unsaturated carbonyl compounds such as tetracyclone (34) and cyclopentenone (27a). Both FMO and transition state calculations correctly predicted the regio- and stereochemistry of the cycloadducts. The calculations further revealed that a severe steric interaction caused by the phenyl rings present in dipolarophile 34 with dipole 14a increases the activation barrier of the transition state during the cycloaddition process.
Facile synthesis of oxatricyclic systems with various ring sizes and substituents
Muthusamy, Sengodagounder,Arulananda Babu, Srinivasarao,Gunanathan, Chidambaram,Suresh, Eringathodi,Dastidar, Parthasarathi,Vir Jasra, Raksh
, p. 6307 - 6318 (2007/10/03)
A series of α-diazo carbonyl compounds having cyclopentanone, cyclohexanone and substituted cyclohexanone units with different tether lengths have been synthesized using diazomethane solution or methanesulphonyl azide. The above synthesized α-diazo carbon
