Synthesis of new chiral cyclic 1,2-diamines and their evaluation as catalysts for enantioselective Diels–Alder reactions

Stereoselective synthesis and characterization of new enantiomerically pure phosphoric acids

“…In designing a novel class of Bronsted acid, we decided to take advantage of Akiyama's work on TADDOL-derived phosphoric acids, where it was demonstrated that cyclic phosphates obtained from benzydryl diols were effective organocatalysts for Mannich-type reaction; on this basis we synthesized structurally new Bronsted acids, which should control the stereochemical outcome of the reaction through the action of two stereogenic centers really close to phosphorous atom, in combination with a stereogenic axis of well-defined absolute configuration 19 ( Fig. 1).…”

“…0 -dimethyldiphenyl-2,2 0 -dialdehyde B was easily prepared in quantitative yield 19 and reacted with an aryl Grignard reagent to afford corresponding diol C in yields higher than 98%, as mixtures of isomers; the diol was then reacted with phosphorous trichloride and hydrolyzed to afford the cyclic phosphite D, which was finally oxidized to phosphoric acid E.…”

“…15 Here, we report the synthesis of a conceptually new class of chiral phosphoric acid, derived from (R)- 6,6 0 -dimethyldiphenyl-2,2 0 -dicarboxylic acid, a chiral scaffold that was already successfully used as chiral template to stereocontrol the synthesis of enantiopure double-helicates on nanometer scale, 16,17 to build macrocyclic phenanthrolinebased chiral ligands for Cu(I)-promoted enantioselective cyclopropanations 18 or chiral cyclic diamines as organocatalysts for Diels-Alder cycloadditions. 19 …”

“…19 F spectra were recorded on a Bruker AC 300 at 282.1 MHz or on a Bruker Avance 500 MHz at 470.5 MHz and were referenced to trichlorofluoromethane (CFCl 3 ) at 0.0 ppm. Optical rotations were obtained on a Perkin-Elmer 241 polarimeter at 589 nm.…”

Synthesis of MacMillan catalyst modified with ionic liquid as a recoverable catalyst for asymmetric Diels–Alder reaction

“…It is a key step for the synthesis of many natural products and pharmaceutical compounds. [7][8][9] Several organocatalysts employed for the enantioselective Diels-Alder reaction are chiral diamines, [10][11][12] hydrazides, [13][14][15][16][17][18][19] and diarylprolinol ether. 5,6 The first enantioselective Diels-Alder reaction was reported by MacMillan and co-workers, involving an organocatalyst, which proceeds by a LUMO-lowering activation mechanism.…”