N-BROMOBIS(P-TOLUENESULFONYL)AMINE AS A NOVEL AND MILD REAGENT FOR CONVERSION OF OXIMES TO CARBONYL COMPOUND

N-Bromobis(p-toluenesulfonyl)amine (NBBTA) is a novel and efficient reagent for the conversion of oximes to their corresponding carbonyl compounds in good yields under mild conditions.     

A practical and scalable process to selectively monofunctionalize water-soluble α,ω-diols

A practical protocol for rapid and scalable synthesis of monofunctionalized α,ω-diols using a simple and inexpensive THP ether protection/deprotection strategy was described. Use of inexpensive DHP source and ease to remove excess water-soluble α,ω-diols and THP ether after deprotection render the process scale-friendly without need of column chromatographic separation. The application of present method was also illustrated in the preparation of heterobifunctional diols and well-defined extended oligo(ethylene glycol).     

(NO3)3CeBrO3: Solvent‐Free Oxidation of Alcohols and Deprotection and Oxidative Deprotection of Trimethylsilyl Ethers

Trinitratocerium(IV) bromate (TNCB) can be used as an efficient reagent for oxidation of alcohols and deprotection and oxidative deprotection of trimethylsilyl ethers under solvent‐free conditions.     

2,6-Dicarboxypyridinium Fluorochromate: A Mild and Efficient Reagent for Oxidative Deprotection of Trimethylsilyl Ethers to Their Corresponding Carbonyl Compounds

Deprotection of trimethylsilyl ethers to their parent aldehydes and ketones in high yields has been carried out using 2,6-dicarboxypyridinium fluorochromate under mild conditions.     

Synthesis and Sequential Deprotection of Triblock Copolypept(o)ides Using Orthogonal Protective Group Chemistry

The synthesis of triblock copolymers based on polysarcosine, poly‐N‐ε‐t‐butyloxycarbonyl‐l ‐lysine, and poly‐N‐ε‐t‐trifluoroacetyl‐l ‐lysine by ring‐opening polymerization of the corresponding α‐amino acid N‐carboxyanhydrides (NCAs) is described. For the synthesis of N‐ε‐t‐butyloxycarbonyl‐l ‐lysine (lysine(Boc)) NCAs, an acid‐free method using trimethylsilylchloride/triethylamine as hydrochloric acid (HCl) scavengers is presented. This approach enables the synthesis of lysine(Boc) NCA of high purity (melting point 138.3 °C) in high yields. For triblock copolypept(o)ides, the degree of polymerization (X_n) of the polysarcosine block is varied between 200 and 600; poly‐N‐ε‐t‐butyloxycarbonyl‐l ‐lysine and poly‐N‐ε‐t‐trifluoroacetyl‐l ‐lysine blocks are designed to have a X_n in the range of 10–50. The polypeptide‐polypeptoid hybrids (polypept(o)ides) can be synthesized with precise control of molecular weight, high end group integrity, and dispersities indices between 1.1 and 1.2. But more important, the use of tert‐butyloxycarbonyl‐ and trifluoroacetyl‐protecting groups allows the selective, orthogonal deprotection of both blocks, which enables further postpolymerization modification reactions in a block‐selective manner. Therefore, the presented synthetic approach provides a versatile pathway to triblock copolypept(o)ides, in which functionalities can be separated in specific blocks.

     

Aluminium Chloride Hexahydrate (AlCl3 · 6H2O): An Efficient,Facile, Mild,And Highly Chemoselective Catalytic Deprotection of Tert-Butyldimethylsilyl (TBS) Ethers

tert-Butyldimethylsilyl (TBS) phenyl / alkyl ethers were cleaved to the corresponding efficiently parent hydroxyl compounds in good yields using catalytic amounts of AlCl₃ · 6H₂O by conventional or microwave-assisted heating in methanol or isopropanol solution. Intramolecular and competitive experiments demonstrated the chemoselective deprotection of TBS ethers in the presence of triisopropylsilyl and tert-butyldiphenylsilyl ethers.     

A concise Pd catalyzed cross coupling reaction along with deprotection for the synthesis of a new series of pyrimidine derivatives

A new series of 2-amino, 4-azepanone, 5-aryl substituted derivatives of pyrimidine compounds were synthesized for the first time from the commercially available 2-amino-4-hydroxypyrimidine. The key step in the reaction is a conceptually new single step palladium catalyzed cross coupling along with the deprotection of N,N-diisopropylformimidamide using bis(triphenylphosphine)palladium(II) dichloride (PdCl₂(PPh₃)₂).     

Synthesis of 1-Bromo-3-butyn-2-one and 1,3-Dibromo-3-buten-2-one

Synthetic procedures for the preparation of 1-bromo-3-butyn-2-one and 1,3-dibromo-3-buten-2-one are given. These compounds are prepared from 2-bromomethyl-2-vinyl-1,3-dioxolane, which can readily be prepared from 2-ethyl- 2-methyl-1,3-dioxolane. The synthetic routes are as follows: 2-bromomethyl-2-vinyl-1,3-dioxolane is converted to 2-(1,2-dibromoethyl)-2-bromomethyl-1,3-dioxolane. Double dehydrobromination with ^tBuOK affords 2-ethynyl-2-bromomethyl-1,3-dioxolane. Formolysis with formic acid gives 1-bromo-3-butyn-2-one. Deacetalized 2-bromoethyl-2-vinyl-1,3-dioxolane was treated with Br₂ and Li₂CO₃/12-crown-4 in tetrahydrofuran to give 1,3-dibrom-3-buten-2-one in moderate yield.