Nuclear magnetic resonance spectra of Di-t-butylaryl carbinols

1972 ◽  
Vol 25 (1) ◽  
pp. 109 ◽  
Author(s):  
RE Gall ◽  
D Landman ◽  
GP Newsoroff ◽  
S Sternhell
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Phenyl Ring ◽  
Variable Temperature ◽  
Activation Parameters ◽  
Low Energy ◽  
Nuclear Magnetic Resonance Spectra ◽  
Hydroxyl Oxygen Atom ◽  
Carbon Carbon Bonds ◽  
General Aspects

The preparation and N.M.R. spectra of five title compounds, none of which were substituted at the aryl 2 or 6 positions, is described. Appreciable (ΔG* c � 1 kcal/mol) barriers to rotation about the sp2-sp3 carbon-carbon bonds exist in this series and the hydroxyl oxygen atom is in the plane of the aryl ring in the energetically favoured conformers. Two unequally populated low energy conformers were identified in the title compounds carrying different substituents at the 3 and 5 positions of the phenyl ring. Some general aspects of the determination of activation parameters from variable-temperature N.M.R. spectra are discussed.

Synthesis, structure, and nonrigidity of Os4(CO)15, Os4(CO)13(PMe3)[P(OMe)3], and Os4(CO)14(CNBut)

1995 ◽  
Vol 73 (7) ◽  
pp. 1223-1235 ◽  
Author(s):  
Frederick W.B. Einstein ◽  
Victor J. Johnston ◽  
Andrew K. Ma ◽  
Roland K. Pomeroy
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectra ◽  
Energy Exchange ◽  
Variable Temperature ◽  
Carbonyl Cluster ◽  
Space Group ◽  
Exchange Processes ◽  
Nuclear Magnetic Resonance Spectra ◽  
Osmium Carbonyl ◽  
C Nmr

The binary carbonyl Os4(CO)15, 1, has been prepared by the addition of Os(CO)5 to Os3(CO)10(cyclooctene)2 at −15 °C. The related clusters Os4(CO)13(PMe3)[P(OMe)3], 2, and Os4(CO)14(CNBu′), 3, have been synthesized from Os4(CO)13(PMe3) and Os4(CO)15(CNBu′), respectively. The crystal structures of 1, 2, and 3 reveal similar planar metal skeletons with short (2.774 (1) − 2.793 (2) Å) and long (2.978 (2) − 3.019 (2) Å) peripheral Os—Os bonds; the hinge Os—Os bond in 1–3 ranges in length from 2.936 (2) to 2.948 (1) Å. The variable temperature 13C nuclear magnetic resonance spectra of 1 and 3 show that both are highly nonrigid in solution even at −120 °C. The mechanism of nonrigidity is believed to be an all-equatorial, merry-go-round carbonyl exchange. The variable temperature 13C nmr spectra of 2 indicate it is rigid on the nmr time scale in solution at −45 °C. Carbonyl exchange is, however, observed in the spectrum at −6 °C. From the mode of collapse of the signals it is believed that the lowest energy exchange processes in 3 involve axial-equatorial, merry-go-round CO exchanges in the two planes that each contain a short Os—Os bond. Crystallographic data for compound 1: space group C2/c; a = 12.802 (3) Å, b = 10.217 (3) Å, c = 16.380 (5) Å, β = 91.39 (2)°; R = 0.044, 1204 observed reflections. For compound 2: space group P21/c; a = 11.106 (7) Å, b = 16.931 (5) Å, c = 16.481 (5) Å, β = 97.71 (5)°; R = 0.051, 2117 observed reflections. For compound 3: space group P21/n; a = 11.747 (3) Å, b = 18.009 (5) Å, c = 12.448 (2) Å, β = 92.65 (2)°; R = 0.054, 2131 observed reflections. Keywords: osmium, carbonyl, cluster, nonrigidity.

Taxonomy and chemistry of a new fungus from bark beetle infested Pinus contorta var. latifolia. Part 2. Arthrographol, the metabolite inhibitory to Ophiostoma clavigerum

1990 ◽  
Vol 36 (2) ◽  
pp. 83-85 ◽  
Author(s):  
William A. Ayer ◽  
Koohei Nozawa
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Mass Spectrum ◽  
Magnetic Resonance ◽  
Pinus Contorta ◽  
Antifungal Compound ◽  
Compound Structure ◽  
Nuclear Magnetic Resonance Spectra ◽  
Blue Stain Fungi ◽  
Blue Stain

The isolation and structure determination of arthrographol (1) is described. This substituted dihydrobenzofuran is the compound responsible for the antagonism shown by the newly described fungus Arthrographis pinicola Sigler and Yamaoka towards some blue stain fungi. The 1H and 13C nuclear magnetic resonance spectra, infrared and ultraviolet spectra, and the mass spectrum of arthrographol and its diacetyl derivative are reported. The inhibitory activity of arthrographol against Ophiostoma clavigerum (≡Ceratocystis clavigera) is described. Arthrographol, a new natural product, appears to be a norheptaketide related to known benzofurans of fungal origin. Key words: antifungal compound, structure of arthrographol, norheptaketide, blue stain fungus, Arthrographis pinicola.

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