91510-99-5Relevant articles and documents
Complementary and stereodivergent approaches to the synthesis of 5-hydroxy- and 4,5-dihydroxypipecolic acids from enantiopure hydroxylated lactams
Scarpi, Dina,Bartali, Laura,Casini, Andrea,Occhiato, Ernesto G.
, p. 1306 - 1317 (2013/04/10)
We describe two complementary and stereodivergent routes, from commercially available and inexpensive starting materials, for the synthesis of 4,5-dihydroxy- and 5-hydroxypipecolic acids based on the chemistry of lactam-derived enol phosphates. The synthesis of the 4,5-cis-4,5- dihydroxypipecolic acids required the preparation from 2-deoxy-D- and -L-ribose of the enantiopure cis-(4S,5R)- and -(4R,5S)-4,5-dihydroxy-δ-valerolactam, respectively. These new chiral synthons are potentially useful for the synthesis of other natural products. The key step is the Pd-catalyzed methoxycarbonylation reaction of the enol phosphates generated from these lactams. This reaction provided enecarbamate esters that were easily converted by stereoselective reduction to the target compounds. The synthesis of the 4,5-trans-4,5-dihydroxypipecolic acid, as well as of 5-hydroxypipecolic acids, was realized from a known (S)-5-hydroxy-δ-valerolactam derivative and, for the dihydroxylated compound, required a highly stereoselective allylic bromination reaction of the enecarbamate ester obtained by methoxycarbonylation of the enol phosphate. The preparation of the (4R,5S) enantiomer of the cis-4,5-dihydroxy-δ-valerolactam from 2-deoxy-L-ribose, alongside the fact that (R)-5-hydroxy-δ-valerolactam can be prepared from (R)-(-)-γ-hydroxymethyl-γ-butyrolactone, means our approach allows for the synthesis of all stereoisomers of these compounds, which can be employed as conformationally constrained scaffolds in drug discovery. The stereoselective synthesis of 5-hydroxy- and 4,5-dihydroxypipecolic acids was accomplished by sequential Pd-catalysed methoxycarbonylation and stereoselective reduction of enantiopure hydroxylated lactam-derived enol phosphates obtained from both enantiomers of commercially available γ-hydroxymethyl-γ- butyrolactone and 2-deoxyribose. Copyright
A Facile and General Entry to Optically Active Pheromones and Aromas With γ-Alkyl-γ-lactone Structures. A Study of Some Lactone Derivatives of Pentoses
Cardellach, J.,Font, J.,Ortuno, R. M.
, p. 327 - 331 (2007/10/02)
A new and easy general methodology has been developed to prepare γ-alkyl-α,β-butenolides or γ-alkylbutyrolactones in four and five steps, respectively, from D-ribonolactone as a common chiral starting material.Some of these products have pheromonal activity in insects and are also used as fruit fragrances.A study on several derivatives of D-ribonolactone and 2-deoxy-D-ribonolactone has been carried out in order to explore alternative routes for these syntheses.
