23963-16-8Relevant articles and documents
Diastereo- And enantioselective synthesis of β-Hydroxy-α-amino acids: Application to the synthesis of a key intermediate for lactacystin
Li, Qiong,Yang, Shao-Bo,Zhang, Zhihui,Li, Lei,Xu, Peng-Fei
supporting information; experimental part, p. 1627 - 1631 (2009/09/24)
The development of a highly efficient and stereoselective methodology for the preparation of β-hydroxy-α- amino acids is described. Nucleophilic addition of enolates of tricyclic iminolactones 1a and 1b to aldehydes in the presence of 6 equiv of lithium chloride in THF at -78 °C leads to aldol adducts in good yield (63-86%) and high diastereoselectivity (up to >25:1 dr). Subsequently, hydrolysis of the aldol adducts under acidic conditions leads to the corresponding β-hydroxy-a-amino acids in good yields (up to 83%) and excellent enantiomeric excesses (99% ee) with good recovery yields of the chiral auxiliaries 6 and 7. This methodology was applied to the facile synthesis of the key intermediate for lactacystin along with several isomers.
Oxazoline N-oxide-mediated [2+3] cycloadditions. Application to a synthesis of (-)-tetrahydrolipstatin
Dirat,Kouklovsky,Langlois, Yves
, p. 753 - 755 (2008/02/12)
Formula presented A [2+3] cycloaddition of camphor-derived oxazoline N-oxide to α,β-unsaturated ester afforded adduct 8. Tetrahydrolipstatin 1 was prepared from this compound in a nine-step sequence of reactions.
Minor Products in Photoreactions of α-Diketones with Arenes. Abstraction of Hydroxylic Hydrogen by Triplet Carbonyl
Rubin, Mordecai B.,Gutman, Arie L.
, p. 2511 - 2515 (2007/10/02)
Photochemical reactions of cyclic saturated α-diketones in toluene or p-xylene produce 1:1 adducts as major products and smaller amounts of reduced diketone and bibenzyls, as expected from previous work.In addition, reaction of BOD gave 2percent of the decarbonylation product, p-methylbenzyl cyclohexyl ketone; reaction of camphorquinone gave a mixture of decarbonylation products (10percent total) including saturated and unsaturated monoketones.These compounds were secondary products arising from reaction of photoexcited diketone with the initially formed adducts; quenching andsensitization studies showed that triplet states of α-diketones were involved in both primary and secondary reactions.The decarbonylation products were also formed by reaction of benzophenone triplets or of tert-butoxy radicals with adducts.Deuterium labeling of the adducts was employed to demonstrate that the decarbonylation process involves abstraction of hydroxylic hydrogen.
