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4457-32-3 Usage

Check Digit Verification of cas no

The CAS Registry Mumber 4457-32-3 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,4,5 and 7 respectively; the second part has 2 digits, 3 and 2 respectively.
Calculate Digit Verification of CAS Registry Number 4457-32:
(6*4)+(5*4)+(4*5)+(3*7)+(2*3)+(1*2)=93
93 % 10 = 3
So 4457-32-3 is a valid CAS Registry Number.
InChI:InChI=1/C8H6ClNO4/c9-8(11)14-5-6-1-3-7(4-2-6)10(12)13/h1-4H,5H2

4457-32-3 Well-known Company Product Price

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  • Aldrich

  • (222801)  4-Nitrobenzylchloroformate  97%

  • 4457-32-3

  • 222801-5G

  • 465.66CNY

  • Detail
  • Aldrich

  • (222801)  4-Nitrobenzylchloroformate  97%

  • 4457-32-3

  • 222801-25G

  • 1,601.73CNY

  • Detail

4457-32-3SDS

SAFETY DATA SHEETS

According to Globally Harmonized System of Classification and Labelling of Chemicals (GHS) - Sixth revised edition

Version: 1.0

Creation Date: Aug 11, 2017

Revision Date: Aug 11, 2017

1.Identification

1.1 GHS Product identifier

Product name 4-Nitrobenzyl Chloroformate

1.2 Other means of identification

Product number -
Other names Carbonochloridic acid, (4-nitrophenyl)methyl ester

1.3 Recommended use of the chemical and restrictions on use

Identified uses For industry use only.
Uses advised against no data available

1.4 Supplier's details

1.5 Emergency phone number

Emergency phone number -
Service hours Monday to Friday, 9am-5pm (Standard time zone: UTC/GMT +8 hours).

More Details:4457-32-3 SDS

4457-32-3Synthetic route

phosgene
75-44-5

phosgene

4-nitrobenzyl chloride
619-73-8

4-nitrobenzyl chloride

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

Conditions
ConditionsYield
In dichloromethane at 20 - 25℃; for 50h;98%
With chloroform at 60 - 65℃; im geschlossenen Rohr;
With 1,4-dioxane
4-nitrobenzyl chloride
619-73-8

4-nitrobenzyl chloride

trichloromethyl chloroformate
503-38-8

trichloromethyl chloroformate

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

Conditions
ConditionsYield
With dmap In toluene at 20℃; for 24h;
rac-Pro-OH
609-36-9

rac-Pro-OH

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

1-(4-nitrobenzyloxycarbonyl)pyrrolidine-2-carboxylic acid
347386-12-3

1-(4-nitrobenzyloxycarbonyl)pyrrolidine-2-carboxylic acid

Conditions
ConditionsYield
With sodium hydrogencarbonate In 1,4-dioxane; water at 0 - 20℃; Shotten-Baumann reaction;100%
2-benzyl-1H-imidazole-4-carbaldehyde
68282-55-3

2-benzyl-1H-imidazole-4-carbaldehyde

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

2-benzyl-4-formylimidazole-1-carboxylic acid 4-nitrobenzyl ester
623906-05-8

2-benzyl-4-formylimidazole-1-carboxylic acid 4-nitrobenzyl ester

Conditions
ConditionsYield
With sodium hydrogencarbonate In 1,4-dioxane; water at 0℃; for 2.5h;100%
With sodium bicarbonate In 1,4-dioxane; water100%
With sodium hydrogencarbonate In 1,4-dioxane; water at 0℃; for 2.5h;100%
2-Ketopiperazine
5625-67-2

2-Ketopiperazine

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

4-p-nitrobenzyloxycarbonyl-2-ketopiperazine
623564-23-8

4-p-nitrobenzyloxycarbonyl-2-ketopiperazine

Conditions
ConditionsYield
With N-ethyl-N,N-diisopropylamine In 1,4-dioxane; dichloromethane at 0℃; for 0.5h;100%
With N-ethyl-N,N-diisopropylamine In 1,4-dioxane; dichloromethane at 0℃; for 0.5h;100%
With N-ethyl-N,N-diisopropylamine In 1,4-dioxane; dichloromethane at 0℃; for 0.5h;100%
With N-ethyl-N,N-diisopropylamine In 1,4-dioxane; dichloromethane; water
(S)-2-tert-butyloxycarbonylamino-4-(piperidin-4-yl)butanoic acid methyl ester
1322746-31-5

(S)-2-tert-butyloxycarbonylamino-4-(piperidin-4-yl)butanoic acid methyl ester

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

(S)-2-tert-butyloxycarbonylamino-4-(1-(4-nitrobenzyloxy)carbonylpiperidin-4-yl)butanoic acid methyl ester
1322746-32-6

(S)-2-tert-butyloxycarbonylamino-4-(1-(4-nitrobenzyloxy)carbonylpiperidin-4-yl)butanoic acid methyl ester

Conditions
ConditionsYield
With triethylamine In tetrahydrofuran at 20℃; for 1.5h; pH=8 - 9;100%
C11H17N3O4

C11H17N3O4

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

8-(tert-butyl) 7-(4-nitrobenzyl) (5S,8S)-2,4-dioxo-1,3,7-triazaspiro[4.4]nonane-7,8-dicarboxylate

8-(tert-butyl) 7-(4-nitrobenzyl) (5S,8S)-2,4-dioxo-1,3,7-triazaspiro[4.4]nonane-7,8-dicarboxylate

Conditions
ConditionsYield
With N-ethyl-N,N-diisopropylamine In tetrahydrofuran for 12h; Inert atmosphere;100%
C11H17N3O4

C11H17N3O4

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

8-(tert-butyl) 7-(4-nitrobenzyl) (5R,8S)-2,4-dioxo-1,3,7-triazaspiro[4.4]nonane-7,8-dicarboxylate

8-(tert-butyl) 7-(4-nitrobenzyl) (5R,8S)-2,4-dioxo-1,3,7-triazaspiro[4.4]nonane-7,8-dicarboxylate

Conditions
ConditionsYield
With N-ethyl-N,N-diisopropylamine In tetrahydrofuran for 12h; Inert atmosphere;100%
C11H17N3O4

C11H17N3O4

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

8-(tert-butyl) 7-(4-nitrobenzyl) (5S,8R)-2,4-dioxo-1,3,7-triazaspiro[4.4]nonane-7,8-dicarboxylate

8-(tert-butyl) 7-(4-nitrobenzyl) (5S,8R)-2,4-dioxo-1,3,7-triazaspiro[4.4]nonane-7,8-dicarboxylate

Conditions
ConditionsYield
With N-ethyl-N,N-diisopropylamine In tetrahydrofuran for 12h; Inert atmosphere;100%
C11H17N3O4

C11H17N3O4

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

8-(tert-butyl) 7-(4-nitrobenzyl) (5R,8R)-2,4-dioxo-1,3,7-triazaspiro[4.4]nonane-7,8-dicarboxylate

8-(tert-butyl) 7-(4-nitrobenzyl) (5R,8R)-2,4-dioxo-1,3,7-triazaspiro[4.4]nonane-7,8-dicarboxylate

Conditions
ConditionsYield
With N-ethyl-N,N-diisopropylamine In tetrahydrofuran for 12h; Inert atmosphere;100%
4R-4-hydroxyproline
51-35-4

4R-4-hydroxyproline

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

(2S,4R)-4-Hydroxy-1-(4-nitrobenzyloxycarbonyl)pyrrolidine-2-carboxylic acid
96034-57-0

(2S,4R)-4-Hydroxy-1-(4-nitrobenzyloxycarbonyl)pyrrolidine-2-carboxylic acid

Conditions
ConditionsYield
With sodium hydroxide In dichloromethane at 0℃; for 2h; Acylation;98%
Stage #1: 4R-4-hydroxyproline; 4-nitrobenzyl chloroformate With sodium hydroxide In dichloromethane; water at 0 - 5℃; for 1h;
Stage #2: With sulfuric acid In water at 0 - 5℃;
93%
Stage #1: 4R-4-hydroxyproline; 4-nitrobenzyl chloroformate With sodium hydroxide In dichloromethane; water at 0 - 5℃; for 1h;
Stage #2: With sulfuric acid In water at 0 - 5℃;
93%
aniline
62-53-3

aniline

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

4-nitrobenzyl phenylcarbamate
74109-32-3

4-nitrobenzyl phenylcarbamate

Conditions
ConditionsYield
With sodium hydrogencarbonate In ethyl acetate at 0℃; for 0.25h;98%
4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

N(α)-tert-butoxycarbonyl-histidine methyl ester
2488-14-4, 149263-87-6

N(α)-tert-butoxycarbonyl-histidine methyl ester

Boc-His[Z(NO2)]-OMe

Boc-His[Z(NO2)]-OMe

Conditions
ConditionsYield
With triethylamine In chloroform at 0 - 20℃; for 2.5h;98%
With triethylamine In chloroform at 0 - 20℃; for 2.5h;98%
(3-bromopropyl)amine
18370-81-5

(3-bromopropyl)amine

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

(3-bromopropyl)-carbamic acid 4-nitrobenzyl ester
78358-91-5

(3-bromopropyl)-carbamic acid 4-nitrobenzyl ester

Conditions
ConditionsYield
With sodium hydroxide In tetrahydrofuran at 20℃; for 2h;98%
(±)-2-endo-amino-3-exo-isopropylbicyclo[2.2.1]heptane hydrochloride

(±)-2-endo-amino-3-exo-isopropylbicyclo[2.2.1]heptane hydrochloride

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

rac-4-nitrobenzyl-(3-exo-isopropylbicyclo[2.2.1]heptan-2-endoyl)carbamate

rac-4-nitrobenzyl-(3-exo-isopropylbicyclo[2.2.1]heptan-2-endoyl)carbamate

Conditions
ConditionsYield
Stage #1: (±)-2-endo-amino-3-exo-isopropylbicyclo[2.2.1]heptane hydrochloride With sodium carbonate In dichloromethane; water at 0 - 20℃; for 0.5h;
Stage #2: 4-nitrobenzyl chloroformate In dichloromethane; water at 0 - 20℃; for 16h; Inert atmosphere;
98%
(pivaloyloxy)methyl 6α-<1(R)-hydroxyethyl>penicillanate
85760-58-3

(pivaloyloxy)methyl 6α-<1(R)-hydroxyethyl>penicillanate

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

(pivaloyloxy)methyl 6α-<1(R)-<<<(p-nitrobenzyl)oxy>carbonyl>oxy>ethyl>penicillanate
124093-83-0

(pivaloyloxy)methyl 6α-<1(R)-<<<(p-nitrobenzyl)oxy>carbonyl>oxy>ethyl>penicillanate

Conditions
ConditionsYield
With dmap; N-ethyl-N,N-diisopropylamine In dichloromethane for 16h; Ambient temperature;97%
(3S,4R)-4-diethoxyphosphinyl-3-<(R)-1-hydroxyethyl>-1-(4-methoxyphenyl)-2-azetidinone
93591-35-6

(3S,4R)-4-diethoxyphosphinyl-3-<(R)-1-hydroxyethyl>-1-(4-methoxyphenyl)-2-azetidinone

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

(3S,4R)-4-diethoxyphosphinyl-1-(4-methoxyphenyl)-3-<(R)-1-(4-nitrobenzyloxycarbonyloxy)ethyl>-2-azetidinone
93591-37-8

(3S,4R)-4-diethoxyphosphinyl-1-(4-methoxyphenyl)-3-<(R)-1-(4-nitrobenzyloxycarbonyloxy)ethyl>-2-azetidinone

Conditions
ConditionsYield
With dmap In dichloromethane for 2h; Ambient temperature;97%
With dmap In dichloromethane79%
N-propyl-6-hydroxyoctylamine
120476-55-3

N-propyl-6-hydroxyoctylamine

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

(6-Hydroxy-octyl)-propyl-carbamic acid 4-nitro-benzyl ester
120476-71-3

(6-Hydroxy-octyl)-propyl-carbamic acid 4-nitro-benzyl ester

Conditions
ConditionsYield
With potassium hydroxide In diethyl ether Ambient temperature;97%
L-threonine methyl ester hydrochloride
39994-75-7

L-threonine methyl ester hydrochloride

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

Z(NO2)-Thr-OMe
219851-78-2

Z(NO2)-Thr-OMe

Conditions
ConditionsYield
With triethylamine In dichloromethane at 0 - 20℃; for 3.5h; Acylation;97%
pipecolic Acid
4043-87-2

pipecolic Acid

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

1-(4-nitrobenzyloxycarbonyl)piperidine-2-carboxylic acid

1-(4-nitrobenzyloxycarbonyl)piperidine-2-carboxylic acid

Conditions
ConditionsYield
With sodium hydrogencarbonate In 1,4-dioxane; water at 0 - 20℃; Shotten-Baumann reaction;97%
1,12-bis(imidazolin-2-yl)dodecane
648440-61-3

1,12-bis(imidazolin-2-yl)dodecane

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

1,12-bis[N,N'-(4-nitrobenzyloxycarbonyl)imidazolin-2-yl]dodecane
648440-67-9

1,12-bis[N,N'-(4-nitrobenzyloxycarbonyl)imidazolin-2-yl]dodecane

Conditions
ConditionsYield
With triethylamine In chloroform at 0 - 20℃;96%
endo-N-hydroxy-5-norbornene-2,3-dicarboxyimide
21715-90-2

endo-N-hydroxy-5-norbornene-2,3-dicarboxyimide

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

N-(4-nitrobenzyl carbonate)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid imide
1154758-31-2

N-(4-nitrobenzyl carbonate)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid imide

Conditions
ConditionsYield
With triethylamine In tetrahydrofuran for 4h;96%
With triethylamine In tetrahydrofuran at 0 - 20℃; for 6h;95.1%
With triethylamine In tetrahydrofuran at 0 - 20℃; for 2h;87.9%
N-hydroxy-5-norbornene-2,3-dicarboximide

N-hydroxy-5-norbornene-2,3-dicarboximide

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

(N-hydroxy-5-norbornene-2,3-dicarboxyl-imido)-4-nitro-benzoate

(N-hydroxy-5-norbornene-2,3-dicarboxyl-imido)-4-nitro-benzoate

Conditions
ConditionsYield
With triethylamine In tetrahydrofuran at 0 - 20℃; for 4h;96%
N-hydroxy-5-norbomene-2,3-dicarboxylic acid imide
1195164-50-1

N-hydroxy-5-norbomene-2,3-dicarboxylic acid imide

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

N-(4-nitrobenzyl carbonate)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid imide
1154758-31-2

N-(4-nitrobenzyl carbonate)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid imide

Conditions
ConditionsYield
With triethylamine In tetrahydrofuran at 0 - 20℃; for 4h;96%
(2S,3S)-S-p-methoxybenzyl-3-methylcysteine allyl ester

(2S,3S)-S-p-methoxybenzyl-3-methylcysteine allyl ester

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

C23H26N2O7S
1374893-41-0

C23H26N2O7S

Conditions
ConditionsYield
With N-ethyl-N,N-diisopropylamine In dichloromethane for 16h; Inert atmosphere;96%
With N-ethyl-N,N-diisopropylamine In dichloromethane Inert atmosphere;
[3-(2-tert-Butoxycarbonylamino-3-hydroxy-propyl)-1H-indol-4-ylamino]-acetic acid ethyl ester
84590-35-2

[3-(2-tert-Butoxycarbonylamino-3-hydroxy-propyl)-1H-indol-4-ylamino]-acetic acid ethyl ester

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

[[3-(2-tert-Butoxycarbonylamino-3-hydroxy-propyl)-1H-indol-4-yl]-(4-nitro-benzyloxycarbonyl)-amino]-acetic acid ethyl ester
84590-36-3

[[3-(2-tert-Butoxycarbonylamino-3-hydroxy-propyl)-1H-indol-4-yl]-(4-nitro-benzyloxycarbonyl)-amino]-acetic acid ethyl ester

Conditions
ConditionsYield
With sodium hydrogencarbonate In diethyl ether; water for 3h; Ambient temperature;95%
methyl 2-methoxy-5-(N-methylamino)phenylacetate
287119-91-9

methyl 2-methoxy-5-(N-methylamino)phenylacetate

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

methyl 2-methoxy-5-[N-methyl-N-(4-nitrobenzyloxycarbonyl)]aminophenylacetate
287119-95-3

methyl 2-methoxy-5-[N-methyl-N-(4-nitrobenzyloxycarbonyl)]aminophenylacetate

Conditions
ConditionsYield
In tetrahydrofuran at 20℃; Acylation;95%
10-triethylsilyl-10-deacetylbaccatin III

10-triethylsilyl-10-deacetylbaccatin III

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

7-p-nitrobenzyloxycarbonyl-10-Triethylsilyl-10 desacetylbaccatin III

7-p-nitrobenzyloxycarbonyl-10-Triethylsilyl-10 desacetylbaccatin III

Conditions
ConditionsYield
With dmap In chloroform at 20℃; for 0.75h;95%
With dmap In dichloromethane94%
4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

(2S,4R)-2-(4-aminomethylthiazol-2-yl)-4-(tert-butyldimethylsilanyloxy)-1-(p-nitrobenzyloxycarbonyl)pyrrolidine
496048-68-1

(2S,4R)-2-(4-aminomethylthiazol-2-yl)-4-(tert-butyldimethylsilanyloxy)-1-(p-nitrobenzyloxycarbonyl)pyrrolidine

(2S,4R)-4-(tert-butyldimethylsilanyloxy)-2-[4-(p-nitrobenzyloxycarbonylaminomethylthiazol-2-yl)]-1-(p-nitrobenzyloxycarbonyl)pyrrolidine
496048-70-5

(2S,4R)-4-(tert-butyldimethylsilanyloxy)-2-[4-(p-nitrobenzyloxycarbonylaminomethylthiazol-2-yl)]-1-(p-nitrobenzyloxycarbonyl)pyrrolidine

Conditions
ConditionsYield
With triethylamine In dichloromethane at 0℃; for 1h;94.2%
3-azidopropylamine
88192-19-2

3-azidopropylamine

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

4-nitrobenzyl (3-azidopropyl)carbamate

4-nitrobenzyl (3-azidopropyl)carbamate

Conditions
ConditionsYield
With sodium hydrogencarbonate In tetrahydrofuran at 20℃; for 24h;94.2%
(3S,4R)-1-(tert-Butyl-dimethyl-silanyl)-4-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-3-((R)-1-hydroxy-ethyl)-azetidin-2-one
85994-38-3

(3S,4R)-1-(tert-Butyl-dimethyl-silanyl)-4-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-3-((R)-1-hydroxy-ethyl)-azetidin-2-one

4-nitrobenzyl chloroformate
4457-32-3

4-nitrobenzyl chloroformate

Carbonic acid (R)-1-{(2R,3S)-1-(tert-butyl-dimethyl-silanyl)-2-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-4-oxo-azetidin-3-yl}-ethyl ester 3-nitro-benzyl ester

Carbonic acid (R)-1-{(2R,3S)-1-(tert-butyl-dimethyl-silanyl)-2-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-4-oxo-azetidin-3-yl}-ethyl ester 3-nitro-benzyl ester

Conditions
ConditionsYield
With dmap In dichloromethane94%

4457-32-3Relevant articles and documents

In vitro radical scavenging and cytotoxic activities of novel hybrid selenocarbamates

Romano, Beatriz,Plano, Daniel,Encío, Ignacio,Palop, Juan Antonio,Sanmartín, Carmen

, p. 1716 - 1727 (2015/03/30)

Novel selenocyanate and diselenide derivatives containing a carbamate moiety were synthesised and evaluated in vitro to determine their cytotoxic and radical scavenging properties. Cytotoxic activity was tested against a panel of human cell lines including CCRF-CEM (lymphoblastic leukaemia), HT-29 (colon carcinoma), HTB-54 (lung carcinoma), PC-3 (prostate carcinoma), MCF-7 (breast adenocarcinoma), 184B5 (non-malignant, mammary gland derived) and BEAS-2B (non-malignant, derived from bronchial epithelium). Most of the compounds displayed high antiproliferative activity with GI50 values below 10 μM in MCF-7, CCRF-CEM and PC-3 cells. Radical scavenging properties of the new selenocompounds were confirmed testing their ability to scavenge DPPH and ABTS radicals. Based on the activity of selenium-based glutathione peroxidases (GPxs), compounds 1a, 2e and 2h were further screened for their capacity to reduce hydrogen peroxide under thiol presence. Results suggest that compound 1a mimics GPxs activity. Cytotoxic parameters, radical scavenging activity and ADME profile point to 1a as promising drug candidate.

Synthesis and structure-activity relationships of nitrobenzyl phosphoramide mustards as nitroreductase-activated prodrugs

Hu, Longqin,Wu, Xinghua,Han, Jiye,Chen, Lin,Vass, Simon O.,Browne, Patrick,Hall, Belinda S.,Bot, Christopher,Gobalakrishnapillai, Vithurshaa,Searle, Peter F.,Knox, Richard J.,Wilkinson, Shane R.

body text, p. 3986 - 3991 (2011/08/06)

A series of nitrobenzyl phosphoramide mustards and their analogs was designed and synthesized to explore their structure-activity relationships as substrates of nitroreductases from Escherichia coli and trypanosomes and as potential antiproliferative and antiparasitic agents. The position of the nitro group on the phenyl ring was important with the 4-nitrobenzyl phosphoramide mustard (1) offering the best combination of enzyme activity and antiproliferative effect against both mammalian and trypanosomatid cells. A preference was observed for halogen substitutions ortho to benzyl phosphoramide mustard but distinct differences were found in their SAR of substituted 4-nitrobenzyl phosphoramide mustards in E. coli nitroreductase-expressing cells and in trypanosomatids expressing endogenous nitroreductases.

Substituent effects on the kinetics of reductively-initiated fragmentation of nitrobenzyl carbamates designed as triggers for bioreductive prodrugs

Hay, Michael P.,Sykes, Bridget M.,Denny, William A.,O'Connor, Charmian J.

, p. 2759 - 2770 (2007/10/03)

4-Nitrobenzyl carbamates are of interest as triggers for bioreductive drugs, particularly in conjunction with the E. coli B nitroreductase, which efficiently reduces them to the corresponding hydroxylamines. These then fragment to release highly toxic amine-based toxins. While many 4-nitrobenzyl carbamate derivatives have been evaluated as bioreductive drugs, there has been no systematic study of substituent effects on the rate of this fragmentation (which should be as fast as possible following reduction). We therefore prepared a series of 2-, 3- and α-substituted 4-[N-methyl-N-(4-nitrobenzyloxycarbonyl)amino]phenylacetamides as model compounds to study these effects. The majority of the carbamates were prepared by in situ formation of the chloroformate of the appropriate 4-nitrobenzyl alcohol and reaction with methyl 4-(methylamino)phenylacetate, followed by ester hydrolysis and 1,1′-carbonyl-diimidazole (CDI) mediated coupling with N,N-dimethylaminoethylamine. The hydroxylamines were generated by 60Co γ-ray irradiation of the nitro compounds in aqueous phosphate-buffered-propan-2-ol. The reactions were analysed by reverse-phase HPLC to determine the maximum half-life (Mt1/2) of the hydroxylamines generated, and the extent of release of amine from these after 10 half-lives (t∞). The parent (unsubstituted) hydroxylaminobenzyl carbamate had a Mt1/2 of 16 min under these conditions, while that of the corresponding α-methyl analogue was 9.5 min. Electron-donating substituents on the benzyl ring also accelerated fragmentation, with the data being fitted to the equation log(Mt1/2) = 0.57σ + 1.30, where σ represents σp for 2-substituents and σm for 3-substituents. The acceleration of fragmentation of the hydroxylamines with increasing substituent electron-donation is consistent with the proposed mechanism, and is presumably due to stabilisation of the developing positive charge on the benzylic carbon. The extent of release of amine (t∞) also increased with increasing substituent electron-donation. These data suggest that the standard 4-nitrobenzyl carbamate trigger for nitroreductase enzyme (NTR) prodrugs can likely be improved on, by increasing the rate of fragmentation by the use of α-methyl and/or electron-donating benzyl substituents. The Royal Society of Chemistry 1999.

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