- On the stereochemistry of the olefinic double bond in 13-membered heterocyclic rings accessible by ring-closing metathesis reaction
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13-Membered heterocyclic ring analogs of the core structure of manzamine alkaloids were synthesized by ring closing metathesis (RCM) reaction. The influence of a remote heteroatom (N, O, S) on E/Z stereochemistry of the olefinic double bond formed in RCM reaction using Grubbs 1st and 2nd generation ruthenium carbene complexes was evaluated. Studies show that RCM reaction is kinetically controlled and the hetero atoms influence the double bond stereochemistry.
- Rao, H. Surya Prakash,Rafi, Shaik,Ratish Kumar,Guravaiah,Muthanna, Nandurka
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p. 6877 - 6880
(2013/01/15)
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- Hydroxy-1-aminoindans and derivatives: Preparation, stability, and reactivity
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The chemical stability and reactivity of hydroxy-1-aminoindans and their N-propargyl derivatives are strongly affected by the position of the OH group and its orientation relative to that of the amino moiety. Thus, the 4- and 6-OH regioisomers were found to be stable, while the 5-OH analogues were found to be inherently unstable as the free bases. The latter, having a para orientation between the OH and the amino moieties, could be isolated only as their hydrochloride salts. 7-Hydroxy-1-aminoindans and 7-hydroxy-1- propargylaminoindans represent an intermediate case; while sufficiently stable even as free bases, they exhibit, under certain experimental conditions, unexpected reactivity. The instability of the 5- and 7-hydroxy-aminoindans is attributed to their facile conversion to the corresponding, reactive quinone methide (QM) intermediates. The o-QM obtained from 7-hydroxy-aminoindans was successfully trapped with ethyl vinyl ether via a Diels-Alder reaction to give tricyclic acetals 32a,b.
- Herzig, Yaacov,Lerman, Lena,Goldenberg, Willy,Lerner, David,Gottlieb, Hugo E.,Nudelman, Abraham
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p. 4130 - 4140
(2007/10/03)
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- Method for producing amines by homogeneously catalyzed reductive amination of carbonyl compounds
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The invention relates to the preparation of chiral or achiral amines by reaction of aldehydes or ketones with ammonia or primary or secondary amines in the presence of hydrogen and in the presence of homogeneous metal catalysts under mild conditions. Metal catalysts which can be used are complexes of late transition metals with chiral or achiral phosphorus-containing ligands.
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Page/Page column 12
(2010/02/11)
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- A mild procedure for the production of secondary amines from oximes and benzisoxazoles
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2-Hydroxybenzaldoximes are reduced under mild conditions of ammonium formate/Pd-C in methanol to give secondary amines. Benzisoxazoles react under the same mild conditions to give the same products. A possible mechanism is suggested, involving the interme
- Searcey, Mark,Grewal, Sukhwant S.,Madeo, Fiorenza,Tsoungas, Petros G.
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p. 6745 - 6747
(2007/10/03)
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- One- and Two-Dimensional NMR Study of Resol Phenol-Formaldehyde Prepolymer Resins
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A one- and two-dimensional NMR study was performed on three commercial resol phenol-formaldehyde (PF) prepolymer resins. 1H, 13C, CSCM and DQF COSY NMR spectral data, in acetone-d6, were obtained on each resin and on PF model compounds: phenol, five methylolphenols, four diphenylmethanes, two formals, two dibenzyl ethers and two dibenzylamines.Gated-decoupled 13C experiments, using 2,4,6-trimethylphenol as internal standard, were used to quantitate the major components present in each of the three resins.The major chemical differences of the three resins were noted.A DQF COSY method was developed that allowed the qualitative identification of most of the major phenolic components present in each of the PF resins. - Keywords: NMR; 1H NMR; 13C NMR; Phenol-formaldehyde resins
- Fisher, Thomas H.,Chao, Ping,Upton, G. Cindy,Day, Anthony J.
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p. 717 - 723
(2007/10/02)
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