ABSTRACT
Paullone isomers are known as inhibitors of tubulin polymerase and cyclin dependent kinases (Cdks), which are potential targets for cancer chemotherapy. Herein we report an efficient and clean pathway to the fourth isomer, which remained elusive so far, namely 7,8-dihydroindolo[2,3-d][1]benzazepin-6(5H)-one. Moreover, we demonstrate the generality of our pathway by synthesizing two closely related analogues, one containing a bromo substituent and the other one incorporating an 8-membered instead of a 7-membered ring. The key transformation in this four-step synthesis, with an overall yield of 29%, is the Fischer indole reaction of 2-nitrophenylacetyl acetoacetate with 1-benzyl-1-phenylhydrazine in acetic acid that delivers methyl 2-(1-benzyl-3-(2-nitrophenyl)-1H-indol-2-yl)acetate in 55% yield.
ABSTRACT
A selenium-catalysed para-hydroxylation of N-aryl-hydroxamic acids is reported. Mechanistically, the reaction comprises an N-O bond cleavage and consecutive selenium-induced [2,3]-rearrangement to deliver para-hydroxyaniline derivatives. The mechanism is studied through both 18 O-crossover experiments as well as quantum chemical calculations. This redox-neutral transformation provides an unconventional synthetic approach to para-aminophenols.
ABSTRACT
An improved synthesis of rings DEF of solanoeclepin A has been achieved from ent-Hajos Parrish ketone. A key tricyclo[5.3.2.01,6]decene intermediate having an additional vinyl group as a precursor of a hydroxyl functionality was synthesized, in which the key steps included (i) a [2,3]-Wittig rearrangement to provide trans-hydroindene with C11(R)-configuration, (ii) the introduction of a vinyl group as a masked OH at C6, (iii) an oxymercurative aldol to synthesize the tricyclo[5.3.2.01,6]decene moiety, (iv) an oxidative C-C bond cleavage to yield an aldehyde and an unsaturated methyl ketone, and (v) a radical cyclization for the cyclobutane ring formation to provide the tricyclo[5.2.1.01,6]decene compound.
Subject(s)
Bridged-Ring Compounds/chemical synthesis , Hexanes/chemical synthesis , Bridged-Ring Compounds/chemistry , Cyclization , Hexanes/chemistry , Molecular ConformationABSTRACT
The highly strained tricyclo[5.2.1.0(1,6)]decene skeleton of solanoeclepin A was synthesized through two key C-C bond forming processes; thus, a Hg(TFA)2-mediated oxymercuration followed an intramolecular aldol reaction to B and a SmI2-mediated cyclization of C between an aldehyde and an unsaturated ester to form the cyclobutane D having a tricyclo[5.2.1.0(1,6)]dodecene.
