41918-08-5Relevant articles and documents
Solid-state and solution structures of several new [LnCp′2(OR)]2 complexes (Ln=Pr, Yb) with chiral, oxygen-functionalized μ-alkoxide ligands
Steudel, Annette,Stehr, Jens,Siebel, Eric,Fischer, R. Dieter
, p. 89 - 96 (1998)
Nine novel organolanthanoid (Ln=Pr and Yb) complexes of the general type [LnCp′2(μ-OCHR(1)Z)]2 (Cp′=C5H5 or CH3C5H4, R(1)=H or Me) containing exclusively ch
Product studies and laser flash photolysis on alkyl radicals containing two different β-leaving groups are consonant with the formation of an olefin cation radical
Bales,Horner,Huang,Newcomb,Crich,Greenberg
, p. 3623 - 3629 (2007/10/03)
1-Bromo-2-methoxy-1-phenylpropan-2-yl (3) and 2-methoxy-1-phenyl-1-diphenylphosphatopropan-2-yl (4) were generated under continual photolysis from the respective PTOC precursors in a mixture of acetonitrile and methanol. The radicals undergo heterolytic fragmentation of the substituent in the β-position to generate the olefin cation radical (5). Z-2-Methoxy-1-phenylpropene (15) is the major product formed in the presence of 1,4-cyclohexadiene, and is believed to result from hydrogen atom transfer to the oxygen of the olefin cation radical, followed by deprotonation. Laser flash photolysis experiments indicate that reaction between 5 and 1,4-cyclohexadiene occurs with a rate constant of ～6 × 105 M-1 s-1. 2,2-Dimethoxy-1-phenylpropane (18) is observed as a minor product. Laser flash photolysis experiments place an upper limit on methanol trapping of 5 at k 3 M-1 s-1 and do not provide any evidence for the formation of reactive intermediates other than 5. The use of two PTOC precursors containing different leaving groups to generate a common olefin cation radical enables one to utilize product analysis to probe for the intermediacy of other reactive intermediates. The ratio of 15:18 is dependent upon hydrogen atom donor concentration, but is independent of the PTOC precursor. These observations are consistent with the proposal that both products result from trapping of 5 that is formed via heterolysis of 3 and 4.
Diastereoselective Conjugate Addition to (+)-Camphorsulfonic Acid Derived Nitroalkenes: Synthesis of α-Hydroxy and α-Amino Acids
Barrett, Anthony G. M.,Braddock, D. Christopher,Christian, Paul W. N.,Pilipauskas, Daniel,White, Andrew J. P.,Williams, David J.
, p. 5818 - 5823 (2007/10/03)
Diastereoselective tandem conjugate addition of both oxygen- and nitrogen-centered nucleophiles to the novel (1S)-10-camphorsulfonic acid derived nitroalkenes 9, 10, and 11 and ozonolysis gave the α-hydroxy and α-amino thiol acid derivatives 12, 13, and 14. In all cases, the (R)-diastereomer was formed as the major component albeit with only modest levels of selectivity (33-71% de). The structures of the products and the stereochemistry of the Michael addition step were unequivocally established by X-ray crystallographic studies of nitroalkenes 9 and 10 and (2S)-12c and (2R)-13a and by alternative syntheses from (S)-alanine, (S)-valine, and ethyl (S)-lactate.
