A chiral Rh–phosphite complex displaying high activity in the enantioselective Rh-catalyzed addition of arylboronic acids to carbonyl compounds: when and why atropos is better than tropos

The use of deoxycholic acid derived tropos and atropoisomeric phosphites as chiral ligands in the Rh-catalyzed enantioselective addition of arylboronic acids to arylaldehydes and 2,2,2-trifluoroacetophenone is presented. Screening of these phosphites showed the high activity of the Rh-complex obtained starting from one of the two atropoisomeric ligands, which afforded complete conversion of the carbonyl compounds in short reaction times under mild reaction conditions and with ee’s of up to 84%. A study aimed at getting information about the different behavior of tropos and atropoisomeric ligands is also reported.

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Methyl 3α-acetyloxy-12α-[(3,3′,5,5′-tetratertbutylbiphenyl-2,2′-diyl)-phosphite]-5β-cholan-24-ateC55H83O7P[α]D28=+92.4 (c 0.75, CH2Cl2)Source of chirality: natural source