The design of chiral ligands plays a central role in the development of chiral catalysts for asymmetric reactions, in which the right combination of a sterically well-defined scaffold with a chelating moiety can lead to excellent enantioselective control in the catalysis.[1] From this point of view, spirobackbones (Scheme 1) have been recognized as one of the privileged structures for the construction of chiral ligands [2] ever since the pioneering work by Chan et al. (SpirOP), Sasai and co-workers, and Zhou and co-workers (SDP).[3] In contrast, van Leeuwen and co-workers reported the development of the bisphosphine ligands SPANphos which have an interesting spiro-2,2'-bis(chroman) backbone and their transition-metal complexes have been studied in catalysis.[4] Despite the success of their rhodium(I) complexes in the catalysis of methanol carbonylation,[4c] the application of spiro-2,2-bis(chroman)-based chiral ligands in asymmetric catalysis still remains relatively unexplored. [4e,g, 5] Very recently, we developed a catalytic asymmetric synthesis of aromatic spiroketals by the tandem hydrogenation and spiroketalization of a,a'-bis(2-hydroxyarylidene)ketones [6a] using Ir/SpinPHOX as the catalyst, [6] and it provides a facile and practical synthesis of a new type of enantiopure analogoue to SPANphos, namely SKP (1). In our ongoing endeavor towards seeking new spirochiral ligands for asymmetric catalysis, we communicate herein our preliminary results on the synthesis of one type of chiral bisphospine ligand having an aromatic spiroketal motif (1; SKP) and their application in palladium-catalyzed enantioselective allylic amination of racemic Morita-Baylis-Hillman (MBH) adducts [7] with aromatic amines. The developed methodology has provided a facile and efficient synthesis of optically active b-lactam derivatives, [8] including the chiral drug Ezetimibe which is used to treat high cholesterol. [9] As shown in Scheme 2, synthesis of the enantiopure spiro-2,2'-bis(chroman)-based bishosphine ligands (R,R,R)-1 is quite simple and straightforward from readily available a,a'-bis(2-hydroxy-3-bromophenylidene)ketone (2) by using our previously published procedure.[6a] The key intermediate, the 3-bromo-substituted aromatic spiroketal (R,R,R)-3 was treated with nBuLi and the resulting lithium salt was reacted with Ar 2 PCl in THF to afford the corresponding enantiopure spiroketal-based bisphosphine ligands (R,R,R)-1 a-f in moderate to good yields (40-80 %) on gram scale.Optically active a-alkylidene-b-arylamino carbonyl compounds represent one type of valuable building blocks with wide applications in the synthesis of medicinally relevant molecules and natural products, [10] but these building blocks are not readily accessible using direct asymmetric aza-MBH reactions because of the electron-rich nature of the corresponding N-aromatic imines. [7,11] In contrast, the enantioselective, metal-catalyzed allylic amination is a useful method for the preparation of enantiomerically enriched allylic amines.[12] Despite the suc...

Palladium-catalyzed regio-, diastereo-, and enantioselective allylic alkylation of β-ketocarbonyls with Morita-Baylis-Hillman adducts has been developed using a spiroketal-based diphosphine (SKP) as the ligand, thus affording a range of densely functionalized products bearing vicinal tertiary and all-carbon quaternary stereodyad in high selectivities. The utility of the protocol was demonstrated by the facile synthesis of some complex molecules by simple product transformations.