1.A convergent Pd-catalyzed asymmetric allylic alkylation of dl- and meso-divinylethylene carbonate: enantioselective synthesis of (+)-australine hydrochloride and formal synthesis of isoaltholactone.
Trost BM1, Aponick A, Stanzl BN. Chemistry. 2007;13(34):9547-60.
The use of a mixture of dl- and meso-divinylethylene carbonate as an electrophile in palladium-catalyzed asymmetric allylic alkylation reactions is reported. From the diastereomeric mixture of meso and chiral racemic starting materials, a single product is obtained in high optical purity employing either oxygen or nitrogen nucleophiles. The resulting dienes have proven to be versatile synthetic intermediates as each carbon is functionalized for further transformation and differentiated by virtue of the reaction. A mechanism for this intriguing transformation is proposed and a concise enantioselective total synthesis of (+)-australine hydrochloride is reported as well as a formal synthesis of isoaltholactone.
2.Stereospecificity in the Au-catalysed cyclisation of monoallylic diols. Synthesis of (+)-isoaltholactone.
Unsworth WP1, Stevens K, Lamont SG, Robertson J. Chem Commun (Camb). 2011 Jul 21;47(27):7659-61. doi: 10.1039/c1cc11805f. Epub 2011 Jun 10.
We describe a concise synthesis of (+)-isoaltholactone via a Au-catalysed cyclisation of a monoallylic diol to form the tetrahydrofuranyl ring. Analogous cyclisations show that the stereochemical outcome is dictated by the stereochemistry of the diol substrate.
3.Cobalt-catalyzed diastereoselective synthesis of C-furanosides. Total synthesis of (-)-isoaltholactone.
Nicolas L1, Izquierdo E, Angibaud P, Stansfield I, Meerpoel L, Reymond S, Cossy J. J Org Chem. 2013 Dec 6;78(23):11807-14. doi: 10.1021/jo401845q. Epub 2013 Nov 12.
An array of C-aryl and C-vinyl furanosides were prepared in good yields and diastereoselectivities from C-halogeno furanosides either with aryl Grignard or with vinyl Grignard using the convenient Co(acac)3/TMEDA catalytic system. This method is illustrated by the total synthesis of the (-)-isoaltholactone.