CANCER-SUSPECT AGENT

A mixture of powdered Mg (0.1 g atom), cyclohexa-1,3-diene (0.1 mol), and TMSCI (0.35 mol) in HMPA (CAUTION—CANCER SUSPECT AGENT) (100 ml) was heated under reflux with stirring for 65 h. After this time, the Mg had disappeared, and the medium had separated into two phases. On cooling, the mixture was poured on to cold saturated ammonium chloride solution, and thoroughly extracted with ether. The combined ethereal extracts were washed with brine and dried. Concentration and distillation gave the silane (0.065 mol, 65%) as a mixture of stereoisomers, b.p. 121-124 °C/25mmHg. 

To a solution of hexamethyldisilane (2.5 mmol) in HMPA (CAUTION— CANCER SUSPECT AGENT) (3 ml) at 0-5 °C was added methyl lithium (2.5 mmol, 1.5 m MeLi.LiBr complex in ether) dropwise. After being stirred for 3 min, the red solution was treated with Cul (2.5 mmol) in Me2S (1 ml), the resulting black reaction mixture was stirred for 3 min. and 2,3-dibromo-propene (1 mmol) was added rapidly via a syringe. The reaction mixture was allowed to warm to room temperature, and was stirred for 1.5 h. It was then poured into pentane (25 ml) and saturated ammonium chloride solution (25 ml, buffered to pH 8 by the addition of ammonium hydroxide), and the mixture was stirred vigorously for 1 h. The aqueous phase was re-extracted with pentane, and the combined organic extracts were dried. Removal of... 

A solution of trimethylsilyl lithium (10 mmol) in HMPA (CAUTION— CANCER SUSPECT AGENT) (5 ml) and ether (10 ml, from the MeLi) prepared as above was cooled to 0°C and diluted with THF (20 ml). Copper(i) cyanide (5 mmol) was added in one portion, and the resulting black mixture was stirred at 0°C for 20min. 

To a solution of potassium methoxide (0.2 mmol) in HMPA (10 ml) (CAUTION—CANCER SUSPECT AGENT), heated to 65°C, was added (E)-oct-4-ene oxide (1.2 mmol), then hexamethyldisilane (1.8 mmol) in HMPA (5ml), and the yellow mixture was stirred at 65°C for 3h. The cooled mixture was poured onto saturated brine, and extracted with pentane (2 x 25 ml). The combined organic extracts were dried and concentrated, to give oct-4-ene (1.15 mmol, 96%, 99 1 (Z) (E) by g.I.c.). 

To a solution of hexamethyldisilane (2.5 mmol) in HMPA (CAUTION— CANCER SUSPECT AGENT) (3 ml) at 0-5 °C was added methyl lithium (2.5 mmol, 1.5 m MeLi.LiBr complex in ether) dropwise. After being stirred for 3 min, the red solution was treated with Cul (2.5 mmol) in Me2S (1 ml), and the resulting black reaction mixture was stirred for 3 min. Ether (6 ml)... 

Early work on the chemistry of organosilyl anions/anionoids has been thoroughly reviewed (/). The most frequently employed preparative routes involve either cleavage of a disilane, when HMPA (CAUTION—CANCER SUSPECT AGENT) is normally required as solvent, or reaction of bulky silyl chlorides with lithium metal. 

To a stirred suspension of NaH or KH (20 mmol) in HMPA (CAUTION— CANCER SUSPECT AGENT) was added hexamethyldisilane (10 mmol) slowly with stirring. A clear yellow-brown solution of trimethylsilyl potassium was obtained immediately mild heating at 30-40 °C is necessary to prepare trimethylsilylsodium. 

To a stirred slurry of copper(i) cyanide (110 mmol) in THF (100 ml), cooled to 0 °C, was added a solution of dimethylphenylsilyl lithium (220 mmol, 1.3 m in THF), and the mixture was stirred at 0°C for a further 30min. After cooling to —78°C, a solution of methyl cinnamate (100mmol) in THF (50 ml) was added, and stirring was continued at —78°Cfor6h. At this time, iodomethane (300 mmol) (CAUTION—CANCER SUSPECT AGENT) was added, and the mixture allowed to warm to ambient temperature with... 

Alternatively (27), when the same procedure was followed using THF containing 5eq. HMPA (CAUTION—CANCER SUSPECT AGENT) (relative to the aldehyde) at —78°C for 15-20s, followed by quenching at —78 °C and isolation, the ( )-enynes were obtained, ( ) (Z) 20 1 to 10 1, 60-64%. 

Acetates themselves normally give a mixture of O- and C-silylated products. However, using TBDMSC1 in the presence of HMPA (CAUTION —CANCER SUSPECT AGENT), pure ketene acetals of the type CH2=C(OR)OTBDMS can be obtained (6). 

A solution of LDA (11 mmol) in THF (30 ml) was cooled to -78°C, and HMPA (CAUTION—CANCER SUSPECT AGENT) (3 ml) then added. To this solution was added dropwise 3-acetoxyoct-l-ene (10 mmol), and then TBDMSC1 (11 mmol) in THF (2 ml) over 5 min. The pale yellow solution was stirred at -78°C for an additional 2 min, and the reaction mixture was allowed to warm to 25DC over 30min. It was stirred at this temperature for a further 2 h, and then quenched with water and pentane. The combined pentane extracts were concentrated, the crude oily silyl ester was dissolved in THF (25 ml) and dilute aqueous HC1 (5 ml, 3 m) and the solution was then stirred for 45 min at 25 °C to complete hydrolysis. The mixture was then poured into aqueous sodium hydroxide (30 ml, I m) and... 

PCC and PDC are cancer suspect agents and must be dealt with care. 

Potassium bromate is a widely used dough conditioner. However, if it is used in excessive quantities in bread products then appreciable residues (> 1 mg/kg) can remain which is of concern since it is a cancer suspect agent. Its routine analysis is laborious, time-consuming and difficult by HPLC, and Cunningham and Warner (2000) described the development of an instrumental neutron activation method for determination of bromine while HPLC was used to determine bromate in selected samples. 

N,N-Dimethylformamide Cancer Suspect Agent Formamide, N,N-dimethyl- (68-12-2), 75, 162... 

The Michael reaction involves conjugate addition of a nucleophile onto an a,P-unsaturated carbonyl compound, or similar system. Such reactions take place in nature as well, and some can be potentially dangerous to us. For example, the a,P-unsaturated ester ethyl acrylate is a cancer suspect agent. This electrophile can react with biological nucleophiles and, in so doing, bind irreversibly to the nucleophile, rendering it unable to carry out its normal functions. A particularly important enzyme that can act as a nucleophile is DNA polymerase, which is responsible for the synthesis of strands of DNA, especially as part of a DNA repair mechanism (see Section 14.2.2). The nucleophilic centre is a thiol grouping, and this may react with ethyl acrylate as shown. 

N,N-Dimethylformanide CANCER SUSPECT AGENT Formanide, N,N-dimethyl- (8,... 

Carbon tetrachloride CANCER SUSPECT AGENT (8) Methane, tetrachloro- (9) (56-23-5)... 

Styrene oxide was purchased from the Aidrich Chemical Company, Inc., and used without purification. Caution Styrene oxide is listed as a cancer suspect agent. 

Hexamethylphosphoramide HIGHLY TOXIC CANCER SUSPECT AGENT Phosphoric triamide, hexamethyl- (8, 9) (680-31-9)... 

Hexamethylphosphoric triamide is toxic and a cancer-suspect agent. 

Dimethylamino)propyl-3-ethylcarbodiimide hydrochloride Carbodiimide, [3-(dimethylamino)propyl]ethyl-, monohydrochloride (8) 1,3-Propanediamine, N -(ethylcarbonimidoyl)-N,N-dimethyl-, monohydrochloride (9) (25952-53-8) N.N-Dimethylformamide cancer suspect agent Formamide, N,N-dimethyl- (8,9) (68-12-2)... 

Caution These reactions should be carried out in a fume hood because dimethyl sulfide is a stench compound, the bromo ester product is a lachrymator, and formaldehyde is a cancer suspect agent. 

Diethyl sulfate Highly toxic cancer suspect agent Sulfuric acid, diethyl ester (8,9) (64-67-5)... 

Bis(diphenylphosphino)propane]nickel(ll) chloride CANCER suspect AGENT Nickel, dichloro(trimethylenebis[diphenylphosphine]]- (8) Nickel, dichloro[1,3-propanediylbisIdiphenylphosphinel-P.P - (9) (15629-92-2)... 

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