1459-01-4Relevant academic research and scientific papers
ORGANOBORANES FOR SYNTHESIS.9. RAPID REACTION OF ORGANOBORANES WITH IODINE UNDER THE INFLUENCE OF BASE. A CONVENIENT PROCEDURE FOR THE CONVERSION OF ALKENES INTO IODIDES VIA HYDROBORATION
Brown, Herbert C.,Rathke, Michael W.,Rogic, Milorad M.,de Lue, Norman R.
, p. 2751 - 2762 (1988)
The reaction of organoborane with iodine is strongly accelerated by sodium hydroxide.Organoboranes derived from terminal alkenes react with the utilization of approximately two of the three alkyl groups attached to boron, providing a maximum of 67percent yield of alkyl iodide.Thus, hydroboration-iodination of 1-decene gives a 60percent yield of n-decyl iodide.Secondary alkyl groups, derived from internal alkenes, react more sluggishly and only one of the three alkyl groups attached to boron is converted to the iodide.Thus, the procedure applied to 2-butene provides a 30percent yield of 2-butyl iodide.The use of disiamylborane bis-(3-methyl-2-butylborane, Sia2BH as hydroborating agent increases the yield of iodides from terminal alkenes since the primary alkyl groups react in preference to the secondary siamyl groups.Consequently, hydroboration of 1-decene with Sia2BH, followed by iodination gives a 95percent yield of n-decyl iodide.The use of methanolic sodium methoxide in place of sodium hydroxide provides alkyl iodides in considerably higher yields.The combination of hydroboration with iodination in the presence of a base provides a convenient method for the anti-Markovnikov hydroiodination of alkenes.The base-induced iodination of organoboranes proceeds with the inversion of configuration at the reaction center, as shown by the formation of endo-2-iodonorbornane from tri-exo-norbornylborane.
2-substituted-(2SR)-2-amino-2-((1SR,2SR)-2-carboxycycloprop-1- yl)glycines as potent and selective antagonists of group II metabotropic glutamate receptors. 1. Effects of alkyl, arylalkyl, and diarylalkyl substitution
Ornstein, Paul L.,Bleisch, Thomas J.,Arnold, M. Brian,Wright, Rebecca A.,Johnson, Bryan G.,Schoepp, Darryle D.
, p. 346 - 357 (2007/10/03)
In this paper, we describe the synthesis of a series of α-substituted analogues of the potent and selective group II metabotropic glutamate receptor (mGluR) agonist (1S,1'S,2'S)-carboxy-cyclopropylglycine (2, L-CCG 1). Incorporation of a substituent on the amino acid carbon converted the agonist 2 into an antagonist. All of the compounds were prepared and tested as a aeries of four isomers, i.e., two racemic diastereomers. We explored alkyl substitution, both normal and terminally branched; phenylalkyl and diphenylalkyl substitution; and a variety of aromatic and carbocyclic surrogates for phenyl. Affinity for group II mGluRs was measured using [3H]glutamic acid (Glu) binding in rat forebrain membranes. Antagonist activity was confirmed for these compounds by measuring their ability to antagonize (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid-induced inhibition of forskolin-stimulated cyclic-AMP in RGT cells transfected with human mGluR2 and mGluR3. We found that while alkyl substitution provided no increase in affinity relative to 2, phenylethyl and diphenylethyl substitution, as in 105 and 109, respectively, were quite beneficial. The affinity of 109 was further enhanced when the two aromatic rings were joined by an oxygen or sulfur atom to form the tricyclic xanthylmethyl and thioxanthylmethyl amino acids 113 and 114, respectively. Amino acid 113, with an IC50 of 0.010 μM in the [3H]Glu binding assay, was 52-fold more potent than 2, whose IC50 was 0.47 μM.
Structure and Conformation of α'-Diphenylphosphinoyl Enones: X-Ray Structure of E-(5SR,6SR)-3,6-Dimethyl-5-diphenylphosphinoyl-7-triphenylmethoxyhept-2-en-4-one
Doyle, Michael J.,Hall, David,Raithby, Paul R.,Skelton, Nicholas,Warren, Stuart
, p. 517 - 524 (2007/10/02)
A series of α'-diphenylphosphinoyl enones has been prepared and their s-cis or s-trans conformations correlated with 1H NMR and IR spectra and an X-ray crystal structure of the title compound.The effect of chelation to cerium(III) is correlated with the r
Conformational interactions between a phenyl ring and a side-chain halide substituent: a 1H NMR and molecular mechanics study of some 2-aryl-1-halopropanes
Cook, Michael J.,Howe, Trevor J.
, p. 957 - 965 (2007/10/02)
1H NMR data are reported for a series of 2-aryl-1-halopropanes.Vicinal coupling constants in the CH2-CH-fragment show that the rotamer populations about the C-C bond are sensitive to para substituents.The ratio of anti-gauche aryl/halide conformers is greatest when the para substituent is the electron-donating ethyl group and least when it is the strongly electron-withdrawing nitro group.This points to a non-steric conformational interaction involving the ring and the sidechain heteroatom.Comparison of the empirical results with conformational preferences predictedfrom molecular mechanics calculations using the COSMIC force field suggests that the interaction serves to enhance the population of the anti arrangement.
