title: Asymmetric total synthesis of (-)-pironetin employing the SAMP/RAMP hydrazone methodology.
abstract: A convergent asymmetric total synthesis of pironetin (1), a polyketide with immunosuppressive, antitumor, and plant-growth regulating activities is described. The synthesis was realized by coupling between the C(8)-C(14) 2 and C(7)-C(2) 15 fragments, respectively, by using a Mukaiyama-aldol reaction. The stereogenic centers of each fragment were generated by employing the SAMP/RAMP hydrazone (SAMP=(S)-1-amino-2-methoxymethylpyrrolidine, RAMP=(R)-1-amino-2-methoxymethylpyrrolidine) methodology as a key step. An asymmetric alpha-alkylation of diethyl ketone permitted the introduction of the C(10) stereogenic center of 2, whereas the stereocenters C(4) and C(5) of 15 were installed by an asymmetric aldol reaction. Finally, the formation of the alpha,beta-unsaturated delta-lactone was achieved by ring-closing metathesis in the presence of catalytic amounts of titanium tetraisopropoxide.
authors.affiliation: Institut für Organische Chemie, RWTH Aachen, Landoltweg 1, 52074 Aachen, Germany. Enders@RWTH-Aachen.de
authors.forename: Dieter
authors.initials: D
authors.lastname: Enders
authors.forename: Sylvie
authors.initials: S
authors.lastname: Dhulut
authors.forename: Daniel
authors.initials: D
authors.lastname: Steinbusch
authors.forename: Audrey
authors.initials: A
authors.lastname: Herrbach
mesh_terms: D006835:Hydrazones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D011753:Pyrones / Q000138:chemical synthesis*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D006835:Hydrazones; D011753:Pyrones; C088446:pironetin