Reactions of primulagenin A. III. Acetyl derivatives and acetyl migration

1976 ◽  
Vol 29 (6) ◽  
pp. 1341 ◽  
Author(s):  
DR Baigent ◽  
OD Hensens ◽  
KG Lewis
Keyword(s):  
Derivatives Of ◽  
Acetyl Migration ◽  
Oxygen Atoms

Procedures have been developed for the preparation of all of the possible acetylated derivatives of primulagenin A (olean-12-ene-3β,16α,28-triol). Acetyl migration has been shown to occur between the oxygen atoms at the 16α- and the 28-positions.

Structural Systematics of 2/4-Nitrophenoxide Complexes of Closed-Shell Metal Ions. I 2-Nitrophenoxides of Group 1

1998 ◽  
Vol 51 (8) ◽  
pp. 707 ◽  
Author(s):  
Jack M. Harrowfield ◽  
Raj Pal Sharma ◽  
Todd M. Shand ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Room Temperature ◽  
Closed Shell ◽  
Aromatic Rings ◽  
X Ray ◽  
Metal Atoms ◽  
Metal Derivatives ◽  
Derivatives Of ◽  
Fourth Coordination ◽  
Group 1 ◽  
Oxygen Atoms

Room-temperature, single-crystal X-ray studies are recorded for the variously hydrated Group 1 metal derivatives of 2-nitrophenol (2-npH = C6H5NO3). A provisional determination is reported for Li(2-np).½H2O, set as monoclinic, P21/c, a 3·535(3), b 15·06(1), c 24·42(2) Å, β 91·7(1)°, Z = 8, conventional R on F currently 0·18 for No 875 ‘observed’ (I > 3σ(I)) reflections. Na(2-np).H2O is monoclinic, C2/c, a 34 ·23(2), b 3·624(4), c 35·48(2) Å, β 91·24(4)°, Z = 24, R 0·060 for No 1371. Rb(2-np).½ H2O is monoclinic, C2/c (isomorphous with the previously determined potassium analogue), a 25·269(9), b 5·381(5), c 12·010(3) Å, β 105·35(3)°, Z = 8, R 0·046 for No 1380. Cs(2-np).½H2O is monoclinic, P21/n, a 7·648(3), b 26·19(1), c 8·713(6) Å, β 111·75(2)°, Z = 8, R 0·061 for No 2347. All compounds except the lithium derivative are two-dimensional polymeric sheets in which the aromatic rings project to either side of a core of metal atoms coordinated by a web of 2-nitrophenoxide oxygen atoms in various bridging functionalities. The lithium compound is a novel ‘stair’ polymer with two crystallographically independent lithium atoms at successive independent Li–O crossbars, the oxygen atoms of which are phenoxide-Oof each of the two independent ligands. The lithium atoms are alternately four- and five-coordinate, the fourth coordination site of the first being occupied by the water molecule oxygen atom, while the fourth and fifth sites of the second are occupied by the cis-2-nitro oxygen atoms of the two ligands

Synthesis, spectroscopic and structural studies of O-methyl and O-isopropyl monothiocarbonate (monoxanthate) derivatives of dimethyl-and diphenyltellurium(IV). Crystal structures of Me2Te[SCO2(i-Pr)]2, Ph2Te[SCO2(i-Pr)]2, Me2TeCl[SCO2Me], and Me2TeBr[SCO2(i-Pr)]

1996 ◽  
Vol 74 (11) ◽  
pp. 1968-1982 ◽  
Author(s):  
John E. Drake ◽  
Robert J. Drake ◽  
Layla N. Khasrou ◽  
Anil G. Mislankar ◽  
Raju Ratnani ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Key Words ◽  
Lone Pair ◽  
Supramolecular Interactions ◽  
Equatorial Position ◽  
Structural Studies ◽  
Cell Parameters ◽  
Distorted Trigonal Bipyramid ◽  
Derivatives Of ◽  
Oxygen Atoms

Monothiocarbonate derivatives of diorganotellurium(IV), R2Te[SCO2R′]2, and R2TeX[SCO2R′], where R = Me, Ph; R′ = Me, i-Pr; X = Cl, Br, and I, have been prepared and characterized by vibrational and 1H, 13C, and 125Te NMR spectroscopy. Me2Te[SCO2(i-Pr)]2 (2): P21/n (No. 14) with cell parameters a = 6.942(6) Å, b = 25.599(3) Å, c = 9.404(6) Å, β = 94.48(6)°, V = 1666(1) Å3, Z = 4, R = 0.0648, Rw = 0.0624; Ph2Te[SCO2(i-Pr)]2 (4): P21/n (No. 14) with a = 12.360(4) Å, b = 12.277(3) Å, c = 15.066(3) Å, β = 102.82(2)°, V = 2229.1(9) Å3, Z = 4, R = 0.0368, Rw = 0.0312; Me2TeCl[SCO2Me] (5); P21/c (No. 14) with a = 5.193(2) Å, b = 18.118(4) Å, c = 9.613(5) Å, β = 91.31(6)°, V = 904.2(6) Å3, Z = 4, R = 0.0396, Rw = 0.0361; and Me2TeBr[SCO2(i-Pr)] (8): P21/n (No. 14) with a = 11.701(2) Å, b = 6.250(2) Å, c = 16.152(2) Å, β = 98.43(1)°, V = 1168.4(4) Å3, Z = 4, R = 0.0369, Rw = 0.0325. In all molecules, the immediate environment about tellurium is that of the saw-horse structure in which the lone pair is assumed to be stereochemically active and occupying an equatorial position in a distorted trigonal bipyramid. In 2 and 5, the terminal oxygen atoms are oriented toward tellurium, whereas in 4, one O(i-Pr) group is oriented toward tellurium, as it is in 8. In the latter cases, the terminal oxygen atoms act as weak bridges to form a pseudo dimeric species in 4 and a pseudo polymer in 8. Supramolecular interactions in 2 and 5 lead to a sulfur-bridged dimer in the former and a chlorine-bridged polymer in the latter. Key words: structure, tellurium, dimethyl, diphenyl, monothiocarbonates.

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