A Facile Route to Functionalized N-Heterocyclic Carbenes (NHCs) with NHC Base-Stabilized Dichlorosilylene

Reaction of IPr·SiCl2 (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

A Facile Route to Functionalized N-Heterocyclic Carbenes (NHCs) with NHC Base-Stabilized Dichlorosilylene

Reaction of IPr·SiCl2 (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

N-Heterocyclic Carbene Stabilized Dichlorosilaimine IPr·Cl₂SiNR

N-Heterocyclic carbene stabilized dichlorosilaimine IPr·Cl2SiN(Diip) (2) has been synthesized by the reaction of dichlorosilylene IPr·SiCl2 (1) with bis(2,6-diisopropylphenyl)carbodiimide (IPr = :C[N(2,6-i-Pr2-C6H3)CH]2, Diip = 2,6-i-Pr2-C6H3). Reaction of 1 with terphenyl azides also affords dichlorosilaimines IPr·Cl2SiN(2,6-Diip2-C6H3) (3) and IPr·Cl2SiN(2,6-Triip2-C6H3) (4) (Triip = 2,4,6-i-Pr3-C6H2). 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

N-Heterocyclic Carbene Stabilized Dichlorosilaimine IPr·Cl₂SiNR

N-Heterocyclic carbene stabilized dichlorosilaimine IPr·Cl2SiN(Diip) (2) has been synthesized by the reaction of dichlorosilylene IPr·SiCl2 (1) with bis(2,6-diisopropylphenyl)carbodiimide (IPr = :C[N(2,6-i-Pr2-C6H3)CH]2, Diip = 2,6-i-Pr2-C6H3). Reaction of 1 with terphenyl azides also affords dichlorosilaimines IPr·Cl2SiN(2,6-Diip2-C6H3) (3) and IPr·Cl2SiN(2,6-Triip2-C6H3) (4) (Triip = 2,4,6-i-Pr3-C6H2). 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

A Facile Route to Functionalized N-Heterocyclic Carbenes (NHCs) with NHC Base-Stabilized Dichlorosilylene

Reaction of IPr·SiCl2 (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

N-Heterocyclic Carbene Stabilized Dichlorosilaimine IPr·Cl₂SiNR

N-Heterocyclic carbene stabilized dichlorosilaimine IPr·Cl2SiN(Diip) (2) has been synthesized by the reaction of dichlorosilylene IPr·SiCl2 (1) with bis(2,6-diisopropylphenyl)carbodiimide (IPr = :C[N(2,6-i-Pr2-C6H3)CH]2, Diip = 2,6-i-Pr2-C6H3). Reaction of 1 with terphenyl azides also affords dichlorosilaimines IPr·Cl2SiN(2,6-Diip2-C6H3) (3) and IPr·Cl2SiN(2,6-Triip2-C6H3) (4) (Triip = 2,4,6-i-Pr3-C6H2). 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

Reactivity Studies of a Stable N‑Heterocyclic Silylene with Triphenylsilanol and Pentafluorophenol

The reaction of the stable N-heterocyclic silylene [CH­{(CCH2)­(CMe)­(2,6-iPr2C6H3N)2}­Si] (1) with triphenylsilanol and pentafluorophenol in a 1:2 molar ratio resulted in quantitative yields of the pentacoordinate silicon-containing compounds [CH­{(CMe)2(2,6-iPr2C6H3N)2}­Si­(H)­{OSiPh3}2] (2) and [CH­{(CMe)2(2,6-iPr2C6H3N)2}­Si­(H)­{OC6F5}2] (3), respectively. Compounds 2 and 3 were formed by O–H bond activation of triphenylsilanol and pentafluorophenol. They were characterized by elemental analysis, NMR spectroscopy, and EI-MS spectrometry. In their solid-state structures the silicon atom is tetracoordinate in 2, whereas it is pentacoordinate in 3

Stereoselective Synthesis of Uridine-Derived Nucleosyl Amino Acids

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

Stereoselective Synthesis of Uridine-Derived Nucleosyl Amino Acids

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

Reactivity Studies of a Stable N‑Heterocyclic Silylene with Triphenylsilanol and Pentafluorophenol

The reaction of the stable N-heterocyclic silylene [CH­{(CCH₂)­(CMe)­(2,6-<i>i</i>Pr₂C₆H₃N)₂}­Si] (<b>1</b>) with triphenylsilanol and pentafluorophenol in a 1:2 molar ratio resulted in quantitative yields of the pentacoordinate silicon-containing compounds [CH­{(CMe)₂(2,6-<i>i</i>Pr₂C₆H₃N)₂}­Si­(H)­{OSiPh₃}₂] (<b>2</b>) and [CH­{(CMe)₂(2,6-<i>i</i>Pr₂C₆H₃N)₂}­Si­(H)­{OC₆F₅}₂] (<b>3</b>), respectively. Compounds <b>2</b> and <b>3</b> were formed by O–H bond activation of triphenylsilanol and pentafluorophenol. They were characterized by elemental analysis, NMR spectroscopy, and EI-MS spectrometry. In their solid-state structures the silicon atom is tetracoordinate in <b>2</b>, whereas it is pentacoordinate in <b>3</b>