Catalytic enantioselective aziridoarylation of aryl cinnamyl ethers toward synthesis of trans-3-amino-4-arylchromans
Catalytic enantioselective one-pot aziridoarylation reaction of aryl cinnamyl ethers has been demonstrated in detail. Combination of suitable copper catalyst and chiral bis-oxazoline ligand was found to be very efficient for asymmetric aziridination followed by intramolecular arylation (Friedel-Crafts) reaction to provide a general and direct method for the synthesis of trans-3-amino-4-arylchromans with high regio-, diastereo- (dr > 99:1), and enantioselectivity (up to 95% ee) with moderate yield. trans-3-Amino-4- arylchroman is an advanced intermediate for the synthesis of chromenoisoquinoline compounds such as doxanthrine, a potent and selective full agonist for the dopamine-D1 receptor.
Hajra, Saumen,Sinha, Debarshi
body text
p. 7334 - 7340
(2011/11/06)
(Cyclopentadienyl)ruthenium-catalyzed regio- and enantioselective decarboxylative allylic etherification of allyl aryl and alkyl carbonates
(Cyclopentadienyl)tris(acetonitrile)ruthenium hexafluorophosphate {[CpRu(NCMe)3][PF6] or (cyclopentadienyl) (I·6-naphthalene)ruthenium hexafluorophosphate {[CpRu(I·6-naphthalene)][PF6]} in combination with a pyridine oxazoline ligand efficiently catalyze the decarboxylative allylic rearrangement of allyl aryl carbonates. Good levels of regio- and enantioselectivity are obtained. Starting from enantioenriched secondary carbonates, the reaction is stereospecific and the corresponding allylic ethers are obtained with net retention of configuration. An intermolecular version of this transformation was also developed using allyl alkyl carbonates as substrates. Conditions were found to obtain the corresponding products with similar selectivity as in the intramolecular process. Through the use of a hemi-labile hexacoordinated phosphate counterion, a zwitterionic air- and moisture-stable chiral ruthenium complex was synthesized and used in the enantioselective etherification reactions. This highly lipophilic metal complex can be recovered and efficiently reused in subsequent catalysis runs. Copyright
Austeri, Martina,Linder, David,Lacour, Jerome
experimental part
p. 3339 - 3347
(2011/02/23)
Enantioselective and regioselective ruthenium-catalyzed decarboxylative etherification of allyl aryl carbonates
A study was conducted to investigate enantioselective and regioselective ruthenium-catalyzed decarboxylative etherification of allyl aryl carbonates. It was observed that allyl aryl carbonates react in the presence of CpRu and pyridylmonooxazoline ligands, to produced branched allyl aryl ethers in high enantiomeric purity and significant regioselectivity. The transformation demonstrated an effective enantioselective decarboxylative etherification. Initial investigations were conducted, using conditions similar to that of the enantioselective rearrangement of allyl β-keto esters. Allyl carbonate was treated with catalytic amounts of CpRu in THF at room temperature. The scope of the asymmetric protocol was also studied with allyl carbonates, with improved conditions.
Austeri, Martina,Linder, David,Lacour, Jerome
experimental part
p. 5737 - 5741
(2009/05/31)
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