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Diol scaffolds have been utilized as highly effective catalysts and ligands in a wide range of catalytic asymmetric transformations. For scaffolds to be successful as broadly used motifs, they should be prepared cheaply through facile routes and be easily handled. Herein, the synthesis of a family of planar chiral diols based on a modular and robust three‐step route is described, which yields catalytically active diols in >99 % de and >99 % ee, with up to seven different chiral elements. These diols have been characterized by X‐ray crystallographic analysis, which provides clear evidence for the likely transition state when applied in the asymmetric hetero‐Diels‐Alder reaction. Without altering the stereochemistry of the catalyst backbone, it is possible to access both enantiomers of the product by varying the substitution of the catalyst at the α‐position. [ABSTRACT FROM AUTHOR]

The enantioselective azo-based α-amination of an aldehyde followed by a Horner–Wadsworth–Emmons-based vinyl sulfone formation is reported. The thus obtained optically active N , N ′-diprotected trans -(phenylsulfonyl)vinyl hydrazine products were then converted into the corresponding N-functionalised trans -(phenylsulfonyl)vinyl amines. Specifically, reaction of 4-phenylbutanal with di- tert -butyl azodicarboxylate (DBAD) in the presence of l - or d -proline, followed by addition of diethyl [(phenylsulfonyl)methyl]phosphonate, gave either enantiomer of di- tert -butyl trans -1-[5-phenyl-1-(phenylsulfonyl)pent-1-en-3-yl]hydrazine-1,2-dicarboxylate. The enantiomeric excesses of the (+)- and (–)-enantiomers prepared in this manner were in the range 86–89%. The conversion of these γ-hydrazino vinyl sulfones into the corresponding γ-amino-substituted compounds was achieved following a Boc deprotection, Zn reduction, N-functionalisation sequence. This three-step sequence was reasonably efficient (approx. 50%) and no erosion of enantiopurity was found to have taken place. The compounds accessed via this process include both enantiomers of tert -butyl trans -[5-phenyl-1-(phenylsulfonyl)pent-1-en-3-yl]carbamate and epimeric dipeptide mimetics including 4-methyl- N -{(S)-1-oxo-3-phenyl-1-[((S , E)-5-phenyl-1-(phenylsulfonyl)pent-1-en-3-yl)amino]propan-2-yl}piperazine-1-carboxamide (also known as K777). [ABSTRACT FROM AUTHOR]