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The polymethylhydrosiloxane-B(C(6)F(5))(3) combination is found to be a versatile carbonyl defunctionalization system under mild and rapid conditions. For the first time, B(C(6)F(5))(3) has been used as a nonconventional Lewis acid catalyst to activate PMHS. Aromatic and aliphatic carbonyl compounds were effectively reduced to give the corresponding alkanes in high yields.

The oligomers of constrained cis-exo-beta-norbornene amino acid were synthesised and characterised by extensive NMR, CD, IR and MD studies. The results showed the formation of both right and left handed consecutive 6-membered hydrogen-bonded strands for [2S,3R] and [2R,3S] enantiomers, respectively.

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Tendencies of forming stable helices of heterooligomers composed of alternating rigid cis-beta-sugar amino acid and flexible beta-hGly motifs have been investigated, using a combination of molecular mechanics, CD, FT-IR, and NMR techniques. The results show that the solution structures of these oligomers exist as robust right-handed 14-helices. Here, we examine the role of conformationally rigid cis-beta-sugar amino acid in preorganizing the conformation of beta-hGly to form the 14-helix. Our findings also show that a right-handed 14-helix can be formed with as few as four properly sequenced heterogeneous residues. These results represent the expansion of the conformational pool of sugar amino acid in the design of well-folded 14-helices, which can be used to develop beta-peptides endowed with biological activity.

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