Rhodium catalyzed arylboronic acid diastereoselective addition

Scheme 1.16 Rhodium(l) catalyzed arylboronic acid diastereoselective addition.

Imines derived from N tert butanesulfinamide also undergo diastereoselective rhodium(I) catalyzed addition of arylboronic acids [61] (Scheme 1.16), a reaction that has been primarily developed for catalytic asymmetric processes (see below). 

A diastereoselective approach to these chiral building blocks was developed by Ellman (Scheme 8.15) [40]. Thus, N-tert-butylsulfinyl aldimines 57 were employed as electrophiles in the rhodium/phosphine 58-catalyzed addition of arylboronic acids. Whereas Ellman s procedure requires heating, Batey discovered that an amine base allows the reaction to take place at ambient temperature [41]. However, it is worth noting that Ellman s process can also be carried out in an enantioselec-tive way by using N-diphenylphosphinoyl aldimines 48 as substrate and Degu-PHOS (56) as ligand (87-97% yield, 88-94% ee) (Scheme 8.14 Figure 8.4). 

Feringa recently reported a highly enantio- and diastereoselective one-pot conjugate arylation/allylation sequence (Scheme 8.42) [120] where the initial rhodium/ phosphoramidite-catalyzed conjugate addition of arylboronic acids in dioxane/ water was complemented by a Barbier-type indium-mediated allylation. 

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