摘要:

The anionic tridentate ligand, [MeGa(N2C3H3)3]−, has been characterized and its coordinating properties studied. It acts as a six-electron chelating ligand to divalent transition metal ions giving complexes of the type, [MeGa(N2C3H3)3]2M (M = Mn, Fe, Co, Ni, Cu, Zn), believed to possess an octahedral MN6core. The ligand also forms numerous carbonyl complexes and its coordinating ability in Mo, W, and Mn carbonyl derivatives is compared with that of similar boron ligands and the η5-C5H5ligand. From ir measurements and bond length data it appears that the [MeGa(N2C3H3)3]−ligand is superior in creating an electron-rich transition metal centre, and it also affords greater steric protection for the central metal. The expected tridentate chelating nature of the new ligand has been demonstrated through a crystal structure determination of the complex [MeGa(N2C3H3)3]Mo(CO)2(η3-C3H5). Crystals of this complex are tetragonal,a = 26.217(3),c = 10.723(2) Å,Z = 16, space groupI41/a. The structure was solved by Patterson and Fourier syntheses and was refined by full-matrix least-squares procedures to a finalRof 0.030 andRwof 0.031 for 2582 reflections withI ≥ 3σ(I).

ISSN:0008-4042    

DOI:10.1139/v78-343

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The principal product from the cyclization of {[3-(5-nitropyridine-2-yl)-amino]pyridine-2-yl}thioaceticacid is 2-{[3-nitropyridine-2-yl)amino]pyridine-2-yl}thioacetyl-8-[(5-nitropyridine-2-yl)amino]-3-oxidopyrido[2,1-b]thiazolium (4). Its structure was determined primarily by1H and13C nmr. [Journal translation]

ISSN:0008-4042    

DOI:10.1139/v78-344

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The diterpenoid metabolites produced when the fungusCyathusafricanusBrodie (Nidulariaceae) is grown in liquid culture have been examined. The known compounds cyathin A3(1) and allocyathin B3(2) were isolated along with four new diterpenoids which have been named cyafrin A4, cyafrin B4, allocyafrin B4, and cyafrin A5. The structures of these substances have been determined by chemical and physical methods to be3a,10a,12a, and15a, respectively. Cyafrin A4(3a), allocyafrin B4(12a), and cyafrin A5(15a) have been correlated with cyathin A3by chemical transformations. The absolute stereochemistry of cyathin A3has been confirmed by the exciton chirality method.

ISSN:0008-4042    

DOI:10.1139/v78-345

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Raman and infrared spectra of multilayer dispersions of 1,2-perdeuterodipalmitoyl-sn-glycero-3-phosphocholine in water are studied as a function of temperature for the CD stretching region. It is found that the bands associated with these vibrations can be used as a sensitive probe to monitor the gel – liquid crystal phase transition which occurs at a lower temperature in the perdeuterated phospholipid than in the corresponding natural (light) lipid.

ISSN:0008-4042    

DOI:10.1139/v78-346

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Excess volumes of binary mixtures of chloroform and bromoform with the followingn-alcohols: methanol, ethanol, andn-propanol have been measured as a function of composition at 303.15 K by a dilatometric method.

ISSN:0008-4042    

DOI:10.1139/v78-347

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Carbon-13 nuclear magnetic resonance spectra have been obtained and fully assignee for a number of 2-methyl-1-{[p-(methylthio) or -(methylsulfinyl}phenyl]methylene}-1H-indene-3- acetic acid derivatives, including the potent anti-inflammatory compound sulindac, 1Z. PairedEandZisomers were studied along with the sulindac sodium salt and ethyl ester in theZseries. Variations in steric crowding inEvs.Zisomers produce chemical shift effects which alternate with the number of intervening bonds. Fluorine substituent effects and19F nuclear spin coupling to13C nuclei, second-order features in off-resonance proton-decoupled spectra, and values of long-range13CH nuclear spin coupling constants have been employed in making a complete set of assignments.

ISSN:0008-4042    

DOI:10.1139/v78-348

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The phase-transfer catalyzed condensation of diethyl bromomalonate (7d) with Michael acceptors8–12leads to cyclopropanes in high yields. More hindered acceptors and other haloesters do not react, while condensation of7dwith crotonaldehyde leads to a 2:1 adduct via a subsequent Darzens condensation. The synthetic potential of the products is also outlined.

ISSN:0008-4042    

DOI:10.1139/v78-349

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Studies on the ABC + E ring construction of the pentacyclic triterpene skeleton are described. Acid-catalysed cyclisation of the mixture of diastereoisomers11led to preferential cyclisation of one isomer to 10-methoxy-2,2,4aβ,6aβ, 12bβ -pentamethyl-1,2,3,4,4a,5,6,6a, 6bα,7,8,12b,13,14-tetradecahydro-1-picenone (12). An X-ray analysis was performed on this compound which crystallizes in the monoclinic space groupP2/c. There are four molecules in the unit cell which has dimensionsa = 6.456(2),b = 42.518(6),c = 8.519(2) Å, β = 100.92(3)°. The structure was solved by direct methods and refined by block-diagonal least-squares to a finalRvalue of 0.042 for all 3234 observed reflections. The molecular structure found by X-ray diffraction confirms the stereochemical reasoning used in the synthetic steps.

ISSN:0008-4042    

DOI:10.1139/v78-350

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The reaction of 2-keto-1β,4aβ-dimethyl-1α-[2-(3-keto-1,4,4-trimethylcyclohexyl)ethyl]-7-methoxy-1,2,3,4,4a,9-hexahydrophenanthrene1aandbwithp-toluenesulphonic acid in boiling xylene yields the rearranged product, 1,10-dimethyl-2-[2-(3-keto-1,4,4-trimethylcyclohexyl)-ethyl]-7-methoxy-3,4-dihydroanthracene (3). Crystals of3are monoclinic, space groupP21/c,Z = 4, witha = 7.2684(3),b = 30.942(2),c = 10.5544(7) Å, β = 98.24(1)°. The structure was determined by direct methods from diffractometer data and refined by block-diagonal least-squares to anRof 0.043 for 1810 observed reflections. The molecule exhibits no unusual geometric features, although positional disorder is apparent in the cyclohexanone moiety.A possible route for the formation of3from1aandbis presented.

ISSN:0008-4042    

DOI:10.1139/v78-351

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The cleavage of methyl pimarate 8,(14) α-epoxide (4) was studied with a variety of acidic reagents. The major products observed were the corresponding Δ7,8-14α-alcohol and dienes. Participation of the vinyl group was not detected.Consideration of the stereoelectronic requirements for cyclisation of olefins with carbonium ions at C-8 of the pimarane skeleton suggest that the pimaranes are not the biogenetic precursors of the tetracyclic diterpenes. A modification of the traditional route is presented as a working hypothesis.

ISSN:0008-4042    

DOI:10.1139/v78-352

出版商:NRC Research Press    

年代:1978

数据来源: NRC