Preferred conformations of methylthio-acetone and -acetophenone, methylsulphonyl-acetone and -acetophenone, from molecular-mechanics and dipole-moment techniques

Spectroscopic and theoretical studies of some N-methoxy-N-methyl-2-[(4′-substituted) phenylsulfonyl]propanamides

“…Table 5 presents selected NBO interactions and the occupancies for donor and acceptor orbitals for g 1 and g 2 conformers of compound 3 taken as representative for the whole series (1)(2)(3)(4)(5).…”

“…Previous spectroscopic (IR, 13 C NMR, UV and UPS), X-ray diffraction and theoretical studies from our laboratory on some b-carbonyl-sulfones YC(O)CH 2 SO 2 R (Y = Me, Ar, NR 2 , OR and SR; R = Me, Ar) [1][2][3][4][5][6][7] indicated that these compounds in gas phase, in solution and in the solid state prefer the gauche conformation between the C@O and CH 2 AS bonds with respect to the cis conformer, excepting the thioester-sulfones [6] for which only the gauche conformers are present both in gas phase and in solution.…”

Experimental and theoretical study of the intramolecular interactions determining the conformation of β-carbonyl sulfoxides

“…These interactions compete with the mesomeric interaction between the (substituted) R group and the carbonyl group to determine the most stable conformation. l 4 -I 8 The balance of the above interactions generally also results in the dominance of the gauche conformation in the gas phase, the stabilization energy deriving from X,, and/or crc-x to x* MOs charge transfer (CT) interactions. In some cases the variation of the R group or even of the nature of its para-substituents from donor to acceptor, may sizeably modify the interaction between the X and CO group, or even stabilize the cis conformation.…”

DNA Polymerase Photoprobe 2-[(4-Azidophenacyl)thio]-2‘-deoxyadenosine 5‘-Triphosphate Labels an Escherichia coli DNA Polymerase I Klenow Fragment Substrate Binding Site,

“…The modeling software used was the Sybyl program package (version 6.01) from Tripos Associates, Inc. (St. Louis, MO). A model of the substituted photoprobe base was constructed using bond lengths and bond angles from similar compounds (Lumbroso et al, 1989;Tomer et al, 1988). Charges for the substituted bases were determined by MNDO semiempirical calculations (MOPAC).…”