Bicyclic molecule

About: Bicyclic molecule is a research topic. Over the lifetime, 29587 publications have been published within this topic receiving 451252 citations. The topic is also known as: bicyclic molecule.

Photoinduced energy and electron transfer processes in supramolecular species. Tris(bipyridine) complexes of Ru(II)/Os(II), Ru(II)/Ru(III), Os(II)/Os(III), and Ru(II)/Os(III) separated by a rigid spacer

Abstract: The bis(bipyridine) bridging ligand 1,4-bis[2-(2,2[prime]-bipyridin-5-yl)ethenyl]bicyclo[2.2.2]octane(bpy-S-bpy), where S is a rigid spacer made of a bicyclooctane unit symmetrically linked to two ethylene-type units in an E, E-configuration, has been synthesized and its complexes (bpy)[sub 2]Ru(bpy-S-bpy)[sup 2+] (Ru[sup II][center dot]A), (bpy)[sub 2]Os(bpy-S-bpy)[sup 2+] (Os[sup II][center dot]A), (bpy)[sub 2]-Ru(bpy-S-bpy)Ru(bpy)[sub 2][sup 4+] (Ru[sup II][center dot]A[center dot]Ru[sup II]), (bpy)[sub 2]Os(bpy-S-bpy)Os(bpy)[sub 2][sup 4+] (Os[sup II][center dot]A[center dot]Os[sup II]), (bpy)[sub 2]Ru(bpy-S-bpy)-Os(bpy)[sub 2][sup 4+] (Ru[sup II][center dot]A[center dot]Os[sup II]) have been prepared as PF[sub 6[minus]] salts. The length of the rigid spacer S is 9 [angstrom], and the center-to-center separation distance in the dinuclear complexes is 17 [angstrom]. In all these novel compounds, each Ru-based and Os-based unit displays its own absorption spectrum and electrochemical properties, regardless of the presence of a second metal-based unit. The homometallic dinuclear compounds exhibit the same luminescence properties as the corresponding mononuclear species, whereas in the heterometallic dinuclear Ru[sup II][center dot]A[center dot]Os[sup II] species 91% of the Ru-based luminescence intensity is quenched by energy transfer to the Os-based unit, whose luminescence is accordingly sensitized (acetonitrile solution, room temperature).

Synthesis and Anti-HIV-1 Activity of Novel 2,3-Dihydro-7H-thiazolo[3,2-a]pyrimidin-7-ones

Abstract: Appropriately substituted 2,3-dihydro-7H-thiazolo[3,2-a]pyrimidin-7-ones 9−12 and 18 were considered as annulated analogues of HEPT (1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine), and some of these compounds were also found active against HIV-1, the most active one being 2,3-dihydro-5-[(3,5-dimethylphenyl)methyl]-3-ethoxy-6-ethyl-7H-thiazolo[3,2-a]pyrimidin-7-one (10b). S-Alkylation of 5-alkyl-6-(arylmethyl)-2-thiouracils 1−4 was performed with 2-bromoacetaldehyde acetals to furnish the S-[bis(alkoxy)ethyl] derivatives 5−8 and with allyl bromide to furnish S-allyl derivatives 17. The target compounds 9−12 were obtained by an N1 regioselective intramolecular cyclization reaction of silylated 5−8 using trimethylsilyl trifluoromethanesulfonate (TMS triflate) as the catalyst. Treatment of the S-allyl derivatives 17 with bromine in dry methylene chloride afforded the 3-(bromomethyl) derivatives 18.

Direct Asymmetric Aldol Reaction of 5H-Oxazol-4-ones with Aldehydes Catalyzed by Chiral Guanidines

Abstract: A new chiral bicyclic guanidine-catalyzed direct catalytic aldol reaction of 5H-oxazol-4-ones with aldehydes has been developed. The present aldol reaction proceeds smoothly with high enantioselectivity using bicyclic guanidines bearing a hydroxy group at the appropriate position, and various combinations of 5H-oxazol-4-ones and aldehydes are applicable. The method provides synthetically useful α,β-dihydroxycarboxylates bearing a chiral quaternary stereogenic center at the α-carbon atom.