Novel hybrid structures of 5'-deoxyuridine and glycine were conceived and synthesized. Such nucleosyl amino acids (NAAs) represent simplified analogues of the core structure of muraymycin nucleoside antibiotics, making them useful synthetic building blocks for structure-activity relationship (SAR) studies. The key step of the developed synthetic route was the efficient and highly diastereoselective asymmetric hydrogenation of didehydro amino acid precursors toward protected NAAs. It was anticipated that the synthesis of unprotected muraymycin derivatives via this route would require a suitable intermediate protecting group at the N-3 of the uracil base. After initial attempts using PMB- and BOM-N-3 protection, both of which resulted in problematic deprotection steps, an N-3 protecting group-free route was envisaged. In spite of the pronounced acidity of the uracil-3-NH, this route worked equally efficient and with identical stereoselectivities as the initial strategies involving N-3 protection. The obtained NAA building blocks were employed for the synthesis of truncated 5'-deoxymuraymycin analogues.

Reaction of IPr x SiCl(2) (1) [IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] with 1-azidoadamantane leads to functionalized N-heterocyclic carbene (NHC) 2. Silyl-substituted NHC 2 reacts easily with 1-azidoadamantane to form triazene 3, in which the exocyclic C=N bond is slightly shorter than those of regular NHC-derived triazines. 2 could serve as a promising ligand for transition metals.

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N-Heterocyclic carbene stabilized dichlorosilaimine IPr 3 Cl 2 SidN(Diip) (2) has been synthesized by the reaction of dichlorosilylene IPr 3 SiCl 2 (1) with bis(2,6-diisopropylphenyl)carbodiimide (IPr = :C[N(2,6-i-Pr 2 -C 6 H 3 )CH] 2 , Diip = 2,6-i-Pr 2 -C 6 H 3 ). Reaction of 1 with terphenyl azides also affords dichlorosilaimines IPr 3 Cl 2 SidN(2,6-Diip 2 -C 6 H 3 ) (3) and IPr 3 Cl 2 SidN(2,6-Triip 2 -C 6 H 3 ) ( 4) (Triip = 2,4,6-i-Pr 3 -C 6 H 2 ). Compounds 2-4 are stable under an inert atmosphere and were characterized by elemental analysis and NMR spectroscopic studies. The molecular structures of 2-4 were determined by single-crystal X-ray analysis.

The reactions of silylenes with organic azides are quite diverse, depending on the substituents of the silylene center and on the nature of the azide employed. Elusive silaimine with three-coordinate silicon atom L(1)SiN(2,6-Triip(2)-C(6)H(3)) (5) {L(1) = CH[(C═CH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)] and Triip = 2,4,6-triisopropylphenyl} was synthesized by treatment of the silylene L(1)Si (1) with a sterically demanding 2,6-bis(2,4,6-triisopropylphenyl)phenyl azide (2,6-Triip(2)C(6)H(3)N(3)). The reaction of Lewis base-stabilized dichlorosilylene L(2)SiCl(2) (2) {L(2) = 1,3-bis(2,6-iPr(2)C(6)H(3))imidazol-2-ylidene} with Ph(3)SiN(3) afforded four-coordinate silaimine L(2)(Cl(2))SiNSiPh(3) (6). Treatment of 2,6-Triip(2)C(6)H(3)N(3) with L(3)SiCl (3) (L(3) = PhC(NtBu)(2)) yielded silaimine L(3)(Cl)SiN(2,6-Triip(2)-C(6)H(3)) (7) possessing a four-coordinate silicon atom. The reactions of L(3)SiN(SiMe(3))(2) (4) with adamantyl and trimethylsilyl azide furnished silaimine compounds with a four-coordinate silicon atom L(3)(N(Ad)SiMe(3))SiN(SiMe(3)) (8) (Ad = adamantyl) and L(3)(N(SiMe(3))(2))SiN(SiMe(3)) (9). Compound 8 was formed by migration of one of the SiMe(3) groups. Compounds 5-9 are stable under inert atmosphere and were characterized by elemental analysis, NMR spectroscopy, and single-crystal X-ray studies.