Synthesis of Oxa-Bridged Analogues of Farnesyltransferase Inhibitor RPR 115135
摘要:
Two synthetic routes to new oxygen-bridged analogues of farnesyltransferase inhibitors are described that follow either a [3 + 2]/[4 + 2] or a [4 + 2]/[3 + 2] sequence of reactions. The first approach has been achieved by reacting the in situ generated phenylisobenzofuran (PIBF) 4 with pyrroline 5a and has led stereoselectively to racemic 18, which was transformed in a few steps into the target molecule 2. The second pathway relies on a key intermediate 6, obtained either by condensation of PIBF with methyl acrylate, followed by a deprotonation/selenation and an oxidation/elimination sequence, or by cycloaddition between PIBF and alpha -phenylselenoacrylate 11, followed by the same oxidation/elimination sequence. The reaction of 6 with amino dipole 7 gives diastereoselective access to pyrrolidine 25, a precursor of the second target 3, an epimer of 2.
Synthesis of Oxa-Bridged Analogues of Farnesyltransferase Inhibitor RPR 115135
摘要:
Two synthetic routes to new oxygen-bridged analogues of farnesyltransferase inhibitors are described that follow either a [3 + 2]/[4 + 2] or a [4 + 2]/[3 + 2] sequence of reactions. The first approach has been achieved by reacting the in situ generated phenylisobenzofuran (PIBF) 4 with pyrroline 5a and has led stereoselectively to racemic 18, which was transformed in a few steps into the target molecule 2. The second pathway relies on a key intermediate 6, obtained either by condensation of PIBF with methyl acrylate, followed by a deprotonation/selenation and an oxidation/elimination sequence, or by cycloaddition between PIBF and alpha -phenylselenoacrylate 11, followed by the same oxidation/elimination sequence. The reaction of 6 with amino dipole 7 gives diastereoselective access to pyrrolidine 25, a precursor of the second target 3, an epimer of 2.
The regioselectivity of arene-catalyzed reductive lithiation of acetals of chlorobenzaldehydes strongly depends on the form of lithium metal employed as a reducing agent. According to previous findings, naphthalene catalyzed reductions run in the presence of lithium powder (high Na content) led to competitive metalations of both aromatic carbon–chlorine and benzylic carbon–oxygen bonds. At variance
Two synthetic routes to new oxygen-bridged analogues of farnesyltransferase inhibitors are described that follow either a [3 + 2]/[4 + 2] or a [4 + 2]/[3 + 2] sequence of reactions. The first approach has been achieved by reacting the in situ generated phenylisobenzofuran (PIBF) 4 with pyrroline 5a and has led stereoselectively to racemic 18, which was transformed in a few steps into the target molecule 2. The second pathway relies on a key intermediate 6, obtained either by condensation of PIBF with methyl acrylate, followed by a deprotonation/selenation and an oxidation/elimination sequence, or by cycloaddition between PIBF and alpha -phenylselenoacrylate 11, followed by the same oxidation/elimination sequence. The reaction of 6 with amino dipole 7 gives diastereoselective access to pyrrolidine 25, a precursor of the second target 3, an epimer of 2.