One-Pot Eschenmoser Episulfide Contractions in DMSO: Applications to the Synthesis of Fuligocandins A and B and a Number of Vinylogous Amides
摘要:
Practical total syntheses of the natural products fuligocandin A (2a) and fuligocandin B (3) have been achieved through a convergent strategy depending on the Eschenmoser episulfide contraction as a key step. Conducting the reaction in DAIS proved to be an efficient and general method for the synthesis of a variety of vinylogous amides, such as azepan-2-ylidenepropan-2-one.
A unified method for direct C4–H halogenation of indoles has been accomplished with the assistance of anthranilic acids as suitable transient directing groups. Exclusive site selectivity (one out of five potential reactive sites) as well as good functional group tolerance was obtained to install three kinds of halogen atoms (Cl, Br and I, respectively) by using inexpensive N-halosuccinimides (NXS)
transition state for hydrolysis of a distorted amide, accelerates the hydrolysis of the corresponding amides 1 a-3 a by a factor of 10(3) at pH 8. The mechanisms of both the uncatalyzed and antibody-catalyzed reactions were studied. Between pH 8 and 12 the uncatalyzed hydrolysis of N-toluoylindoles 1 a and 3 a shows a simple first-order dependence on [OH(-)], while hydrolysis of 3 a is zeroth-order
A practical synthesis of the biologically active cycloanthranilylproline derivatives fuligocandines A and B is described, starting from L-proline and isatoic anhydride, employing an Eschenmoser episulfide contraction as the key step. (C) 2009 Elsevier Ltd. All rights reserved.
One-Pot Eschenmoser Episulfide Contractions in DMSO: Applications to the Synthesis of Fuligocandins A and B and a Number of Vinylogous Amides
Practical total syntheses of the natural products fuligocandin A (2a) and fuligocandin B (3) have been achieved through a convergent strategy depending on the Eschenmoser episulfide contraction as a key step. Conducting the reaction in DAIS proved to be an efficient and general method for the synthesis of a variety of vinylogous amides, such as azepan-2-ylidenepropan-2-one.