Mechanism of the von Braun amide degradations with carbonyl bromide or phosphorus pentabromide

Phillips, B. A.; Fodor, Gábor; Gál, J.; Letourneau, F.; Ryan, J. J.

doi:10.1016/s0040-4020(01)93483-0

Cited by 25 publications

(12 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Syntheses of N-nitroso compounds: We synthesized a series of N-nitroso compounds from readily available starting materials by established methods. [16][17][18][19] Accordingly, N-methyl-N-nitrosoaniline (2) was obtained in 86 % yield by N-demethylation/N-nitrosation of N,N-dimethylaniline (1) with nBuONO (Scheme 1). Compound 5, bearing an N-nitroso moiety attached to a sulfonyl group, was generated in 54 % yield by amidation of p-toluenesulfonyl chloride (3) followed by N-nitrosation with NaNO 2 (Scheme 2).…”

Section: Resultsmentioning

confidence: 99%

Photochemical Activities of N‐Nitroso Carboxamides and Sulfoximides and Their Application to DNA Cleavage

Hwu

Huang

Tsai

et al. 2009

Chemistry A European J

View full text Add to dashboard Cite

N-Nitroso compounds containing benzene, fluorene or fluorenone rings were synthesized. Photolysis of these compounds with 312-nm UV light provided the NO(*) species, the presence of which was corroborated by use of an EPR method and of 2-phenyl-4,4,5,5-tetramethylimidazolin-1-oxyl 3-oxide (PTIO) as a trapping agent. During irradiation of N-methyl-N-nitroso-9-fluorenone carboxamide (14 c) in the absence of PTIO, it underwent decomposition followed by recombination to give the heterocyclic nitric oxide radical 15. Incorporation of intercalating moieties endowed the N-nitroso compounds with DNA-cleaving ability through single-strand scission upon UV irradiation in a phosphate buffer (pH 5.0-8.0) under aerobic conditions.

show abstract

Section: Resultsmentioning

confidence: 99%

Photochemical Activities of N‐Nitroso Carboxamides and Sulfoximides and Their Application to DNA Cleavage

Hwu

Huang

Tsai

et al. 2009

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…In situ IR spectroscopy with 1 a illustrated the possible reaction course (Figure 1 a–d) 18. As shown in Figure 1 a, the addition of oxalyl bromide to 1 a in 1,2‐dichloroethane at 0 °C caused the chemoselective transformation of the lactam ($\tilde \nu$ =1683 cm −1 , CO stretch) into the bromoiminium intermediate ($\tilde \nu$ =1644 cm −1 , CO stretch)19 without affecting the azido group ($\tilde \nu$ =2104 cm −1 , NN stretch). When the reaction mixture was warmed from 0 °C to 25 °C (Figure 1 b), the peaks derived from the bromoiminium intermediate and azido function diminished gradually, accompanied by evolution of N 2 gas.…”

Section: Methodsmentioning

confidence: 99%

An Efficient Synthesis of Bicyclic Amidines by Intramolecular Cyclization

2004

View full text Add to dashboard Cite

Bicyclic amidines and guanidines are organic superbases utilized in various synthetic transformations. Recently, chiral guanidines have been widely explored as non-metal-containing bases in asymmetric synthesis [1] as well as in asymmetric phase-transfer catalysis. [1d, 2] In spite of great success in catalysis with chiral guanidine derivatives, asymmetric reactions with chiral derivatives of bicyclic amidines [3] have not been widely studied, possibly because of the difficulty of synthesizing chiral bicyclic amidines. The nucleophilic character of bicyclic amidines [3c, 4] further broadens their utility as catalysts. Considering the potency of chiral bicyclic amidines as organocatalysts, the development of an efficient protocol for the synthesis of these compounds would greatly contribute toward the progress in this area. [5] For the formation of a bicyclic amidine, the starting material should have two nitrogen-containing functionalities that can assemble intramolecularly to form an amidine core at the ring junction. Previous reports [3, 6] indicate that the intramolecular attack of a free amino group on a lactam in the presence of a strong acid (p-toluenesulfonic acid or TiCl 4 ) [6a] in refluxing xylene, and the intramolecular attack of a Boc-protected amino group (Boc = t-butoxycarbonyl) to a thiolactam under acidic conditions [3a,b, 6c] are reliable (Scheme 1). However, the former method requires harsh reaction conditions, and the latter, too many steps from readily available organic materials although the reaction conditions are mild. We report a concise synthetic procedure for bicyclic amidines starting from readily available tethered azido lactams by means of an intramolecular cyclization (Scheme 1), which provides easy access to various achiral and chiral bicyclic amidines under mild reaction conditions. The direct use of an azido function, instead of an amino group, plays a key role in our reaction design. We also describe mechanistic aspects of the reaction based on an in situ IR study.We focused on the use of an azido group as the nucleophile in the intramolecular cyclization. [7,8] Although

show abstract

“…Because of this versatility, even existing QATBs need to be further explored and therefore, development of improved synthetic protocols for already existing quaternary ammonium tribromides has also got an importance of its own [20][21][22][23][24][25][26][27] . As case in point, tetrapropylammonium tribromide (TPATB) had been earlier reported but only scanty information with regard to this reagent could be obtained, revealing earlier methods of preparation of TPATB using carbonyl bromide 28 under N 2 and also bromine 29 .…”

Section: Introductionmentioning

confidence: 99%

Tetrapropylammonium Tribromide - An Efficient Reagent for Solvent-Free Brominations

2014

Chem Sci Trans

View full text Add to dashboard Cite

Tetrapropylammonium tribromide (TPATB) has been synthesized by a new environmentally benign protocol and its behavior as brominating reagent under solvent-free conditions studied. The reagent shows efficiency as a solvent-free brominating agent in both hotair oven at elevated temperature as well as in microwave reactor, thus proving it to be a noteworthy addition to the existing organic tribromide reagents.

show abstract

Mechanism of the von Braun amide degradations with carbonyl bromide or phosphorus pentabromide

Cited by 25 publications

References 29 publications

Photochemical Activities of N‐Nitroso Carboxamides and Sulfoximides and Their Application to DNA Cleavage

Photochemical Activities of N‐Nitroso Carboxamides and Sulfoximides and Their Application to DNA Cleavage

An Efficient Synthesis of Bicyclic Amidines by Intramolecular Cyclization

Tetrapropylammonium Tribromide - An Efficient Reagent for Solvent-Free Brominations

Contact Info

Product

Resources

About