Preparation and Use of Carbonyl-decorated Carbenes in the Activation of White Phosphorus

The overall goal of this procedure is to synthesize two different carbonyl decorated carins and explore their reaction with elemental phosphorus. This is accomplished by first synthesizing the two Carine precursors by treating NN prime dimethyl form amadine with either dimethyl lanin dichloride, or three chloro val oil chloride respectively in the presence of triethyl amine at low temperature. The second step is to extract and filter the carbine precursors away from the triethyl ammonium chloride byproduct.

Next, the carbine precursors are deprotonated in benzene using sodium hexa ethyl diol azide to afford the free carbine. The final step is filtration of the carbine solution to remove precipitated sodium chloride followed by evaporation of the solvent. Ultimately, results can be obtained, which highlight the differing electro felicities of these two carine by preparing two dramatically different phosphorus containing compounds.

This method will allow synthetic chemists of all skill levels to prepare these unique carins in high purity and yield. Generally, individuals that are new to this method will struggle at the beginning because they’re not yet proficient in excluding all air and moisture during the filtration of the Carine precursors. Visual demonstration of this technique is critical as the filtration and cannulation steps are difficult to learn by chemist.

New to Schlink line techniques Demonstrating this procedure will be Antonio Torres, an undergraduate research student for my research laboratory. First connect an oven dried 100 milliliter flank flask to a high performance vacuum manifold. After evacuating the flask and flushing with nitrogen, add a stir bar and 1.5 grams of NN prime dimethyl form amadine to the flask.

After capping the flask with a rubber septum, add 30 milliliters of dry degas di chloro methane, followed by 1.1 milliliters of triethyl amine to the flask through the rubber septum using a syringe. Cool, the resulting solution to zero degrees Celsius in an ice bath. Following this add dropwise 0.75 milliliters of dimethyl melanin dichloride to the cooled solution.

Upon addition, allow the solution to stir at zero degrees Celsius under an atmosphere of nitrogen. Once the solution has stirred for one hour, remove all the volatile materials under vacuum. When finished, add 24 milliliters of a two to one mixture of dry Degas hexanes and di chloro methane to the residue in the reaction flask.

Let the mixture tri rate for 10 minutes. Meanwhile, attach a filter tube equipped with a medium porosity glass frit to the top of an oven dried 100 milliliter flank flask to the filter tube. Add enough oven dried seal light to create a filter plug approximately two inches tall after sealing the filter tube with a rubber septum pull vacuum on the system by attaching the flank flask to the vacuum manifold.

Once the filtration apparatus has been assembled and is under vacuum, transfer the white suspension in the reaction flask via cannula into the filter tube. Be sure to periodically pull vacuum on the collection flank flask to ensure that all of the solution filters through the sea light. Next, wash the sea light by adding 18 milliliters of a two to one mixture of dry Degas hexanes and chloro methane using a syringe through the rubber septum.

Again, periodically pull vacuum on the collection flank flask to ensure that all of the solution filters through the sea light. After disconnecting the collection, flank flask from the filter tube under a flush of nitrogen. Seal the collection flank flask with a glass stopper.

Remove all of the solvent from the collection. Flank flask under vacuum to afford the precursor for DTO carbine as an air and moisture sensitive white powder in approximately 92%yield. Verify the product by proton and carbon NMR spectroscopy using deuterated chloroform.

Then transfer the compound into a glove box for storage prior to the next step. To prepare the DTO carbine first transfer an oven dried 100 milliliter flank flask equipped with a stir bar and a glass stopper into a nitrogen filled glove box. Weigh out 0.6 grams of the carbine precursor and 0.267 grams of sodium hexa methyl dyl azide and place both solids into the flank flask.

Add 25 milliliters of dry degas benzene to the two solids in the sch flank flask, and then stopper the flask. After removing the flank flask from the glove box. Stir the Carine solution at room temperature for 30 minutes.

After setting up a filtering apparatus similar to the one described previously, filter the carbine solution as described for the dito carbine precursor. Once the solution has been filtered, remove all of the volatiles using vacuum to afford the crude carine as a yellow orange powder. Further purify the carbine by washing the solid with approximately 10 milliliters of cold hexanes to afford analytically pure compound as an air and moisture sensitive white powder in approximately 85%yield, verify the product by proton and carbon NMR spectroscopy.

Using deuterated benzene, the mono carbine can be prepared similarly to the dito carbine that was just described. Using three chloro paval oil chloride in place of dimethyl mallin dichloride During the synthesis of the carbine precursor to make arus phospho alkyl phosphate weigh out 0.1 grams of the dto carbine and 0.011 grams of white phosphorus or P four inside of a nitrogen filled glove box with the lights turned off. Following this, add the two solids and a magnetic stir bar to a 20 milliliter glass vial wrapped in aluminum foil.

Add 10 milliliters of dry degas dathyl ether to the solids and then cap the vial. Stir the slurry in the dark for two hours, forming a bright red orange precipitate. During the course of the reaction after the reaction is complete, isolate the red solid via filtration using a 10 milliliter medium porosity glass fritted bookner funnel.

Wash the red solid four times with five milliliters of dathyl ether and then dry it under vacuum to afford the analytically pure, stable desired compound in approximately 82%yield. Verify the product by proton and phosphorus NMR spectroscopy using deuterated benzene to make a carine stabilized. P eight allotrope weigh out 0.1 grams of the previously prepared mono carbine and 11.4 milligrams of P four inside of a nitrogen filled glove box with the lights turned off.

After adding the solids and a magnetic stir bar to a 20 milliliter glass vial wrapped in aluminum foil, add 10 milliliters of dry degas ethyl ether to the solids and then cap the vial. Stir the slurry in the dark for two hours, forming a bright orange precipitate. During the course of the reaction following reaction completion, isolate the orange solid via filtration using a 10 milliliter medium porosity glass fritted bookner funnel.

After washing the orange solid four times with two milliliters of dathyl ether, dry it under vacuum to afford the desired air stable compound in approximately 51%yield. Verify the product by proton and phosphorus NMR spectroscopy using deuterated tetra hydro furan. To prepare the desired cyclo edition product, weigh out 0.3 grams of the mono carbine and 51.3 milligrams of P four separately inside of a nitrogen filled glove box with the lights turned off.

After adding P four and 18 milliliters of dry DGAs hexanes to a 20 milliliter glass vial wrapped in aluminum foil, add two milliliters of two three dimethyl one three buty. Dine to the P four suspension in hexanes. While the P four suspension is rapidly stirring, add the carbine as a solid in one portion, turning the suspension bright yellow.

After stirring the suspension for four hours, isolate the yellow solid via filtration using a 10 milliliter medium porosity glass fritted bookner funnel. Concentrate the yellow supernatant solution to dryness and combine the yellow residue with the filtered yellow solid. To purify the crude compound rech, crystallize the combined yellow solids using 12 milliliters of a one to three mixture of di chloro methane and hexanes in a negative 30 degree Celsius freezer in the glove box overnight.

After isolating the pure air stable yellow crystalline product, characterize it by proton and phosphorus NMR spectroscopy. Using derated benzene the ability to isolate ariss phospho alkyl phosphate from white phosphorus relies on the use of an electrophilic carine to activate the P four tetrahedron. Therefore, it is critical to prepare carine with enhanced pi acidity and electro felicity by removing one of the carbonyl moieties to afford mono carbine.

Two, the PI acidity of the dito carbine can be attenuated. The electronic properties of carine have been shown to govern the activated phosphorus product identity. With the more electrophilic dia carbine one tris phospho kinal phosphate three can be prepared in 82%yield.

However, when the less electrophilic mono carbine two is used, the P eight ALLOTROPE four can be isolated in 51 to 75%yield switcher ionic intermediate A has been suggested as forming upon activation of the P four tetrahedron with the more electrophilic dia. Carbine one A is sufficiently nucleophilic to add to the empty P orbital of one resulting in the formation of three through intermediate B.When the less electrophilic Carine two is used A is not sufficiently nucleo ilic to add a third molecule of two and rearranges to afford diphosphate intermediate CC then rapidly undergoes a two plus two cyclo edition dimerization to afford the P eight allotrope four. Intermediate C was verified by trapping with two three dimethyl one three buty DNE to afford five in 71%yield.

Proton NMR spectra for Carine one and two are shown here. Phosphorus, NMR spectra for compounds three, four, and five are displayed here. Once mastered, any chemist should be able to synthesize a desired carbonyl decorated carine in about two days it performed properly.

Don’t forget that working with any of the acid chlorides and more specifically, white phosphorus can be extremely hazardous, and precautions such as working on schlink lines or in a glove box should always be taken.