Needle, double-ended

To a solution of 3.5 uiL (25 mmol) of trimethylsilylacetylcne in 40 mL of THF are added dropwise, at — 78 °C, 10.4 mL of 2.5 M BuLi (26 mmol) in hexane. After stirring for 15 min at —78 X, 25 mL of 1 M 9-methoxy-9-borabicyclo[3.3, l]nonane in hexane are added. The mixture is stirred at —78 "C for a further 1.5 h. Then, 4 mL (33 mmol) of BF3 OEt2 are added and the mixture is stirred for an additional 15 min at — 78 °C before being allowed to warm to r.t. The volatiles are evaporated under reduced pressure to afford a white solid. After the addition of 25 mL of pentane, the suspension is stirred for a few minutes and allowed to settle. The supernatant liquid is decanted into a second flask via a double-ended needle. This procedure is repeated twice, each time with 10 mL of pentane. The combined pentane solution is cooled to — 78 X to precipitate the product. The mother liquor is removed and the crystals are dried under vacuum to afford an extremely hygroscopic, white crystalline material yield 6.52 g (90%). 

E. Quench and purification. While the butyllithium addition is taking place, an acidic ethanol quench solution is prepared in a 3-L, two-necked, round-bottomed flask, equipped with a mechanical stirrer and a 250-mL, pressure-equalizing dropping funnel. The flask is charged with 1 L of absolute ethanol and the funnel with 250 mL of acetyl chloride. The ethanol is stirred rapidly and the flask is cooled with an ice bath as the acetyl chloride is added over a 30-40-min period and then the cooling bath is removed and stirring is continued for 20-30 min. After the main reaction mixture has been stirred for 30 min at room temperature, it is cooled with a dry ice-acetone bath. The acidic ethanol solution is cooled with an ice bath and the cold, main reaction mixture is quenched by addition (via a double-ended needle) into the rapidly stirred, cold, acidic ethanol solution over a 3 to 3.5 hr period (Note 16). 

The lithium tetramethylpiperidide solution from Part A is cooled with a dry ice-acetone bath. When the solution of ethyl 1-naphthoate and dibromomethane has cooled to -74°C or below (internal solution temperature), addition of the dry ice-acetone cooled solution of lithium tetramethylpiperidide is begun. Addition is made via a double-ended (16 gauge) needle over a 40 to 50-min period using a slight positive nitrogen pressure in the 500-mL flask (Note 7). During this time, the addition rate is slowed or stopped as needed to maintain the reaction temperature below -67 C. 

The checkers used butylllthlura purchased from Lithium Alkyls which was standardized by titration with 2,5-dlmethoxybenzyl alcohol. The submitters used butylllthlum obtained from Aldrich Chemical Company, Inc. as a 1.55 M solution In hexanes which was measured by transfer to a septum-capped 250-mL graduated cylinder with a 15-gauge cannula and nitrogen back pressure. This solution was then transferred to the flask containing THF In the same manner. The THF must be cooled prior to addition of the butylllthlura. Stainless steel double-ended needles of the type used by the submitters are available from Aldrich Chemical Company, Inc. and Ace Glass, Inc. 

An oven-dried. 50-mL, 3-necked flask equipped wilh a pressure-equalizing dropping funnel, reflux condenser, nitrogen inlet, magnetic stirrer, and vacuum takeoff adapter is evacuated (vacuum pump) and refilled three times with nitrogen. 10 mL of THF and 0.735 mL (5.25 mmol) of diisopropylamine are then added via a double-ended needle. The solution is cooled to 0"C and 2.2 mL of a 2.4 M solution of butyllithium (5.25 mmol) in hexane are added. The lithium diisopropylamide is allowed to form at 0 °C for 15 min and is then cooled to — 20 C. 5 mmol of the chiral acyclic ketone iminc in 5 mL of THF are added (5 min) and anion formation allowed to continue for 1 h at 20 C. The anion solution is then heated to reflux for 2 h and cooled to —78 C. A solution of 5.25 mmol of the iodoalkane in 5 mL of THF is then added, and alkylation is allowed to proceed at — 78 °C for 1 h. Workup and hydrolysis, as described for the cyclic ketones (see Section 1.1.1.4.1.2.L), yields the a-alkylatcd acyclic ketones (see Table 4). 

An alternative to the syringe technique for the transfer of liquids uses the double-ended needle and is suitable when it is not necessary to know precisely the volume of liquid being transferred, or when the volume is being measured in some other way, e.g. by transfer from a septum-capped measuring cylinder. This... 

Reaction vessels used in this procedure were flame dried under vacuum and all operations carried out in an oxygen-free, argon or nitrogen atmosphere. To a solution of 465.7 mg (2.3019 mmol) of 4,4-dimethyl-6-ethynyl-thiochroman in 4 ml of dry tetrahydrofuran at 0°C was added dropwise 1.5 ml of 1.6 M (2.4 mmol) n-butyl lithium in hexane. This was stirred at 0°C for 10 min and at room temperature for 10 min, cooled again to 0°C and then treated with a solution of 330 mg (2.4215 mmol) of fused ZnCI2 in 4 ml dry tetrahydrofuran using a double ended needle. Thereafter the... 

Dry, gas-tight syringes, steel needles, and a double-ended needle... 

Transfer the Grignard solution into the second two-necked flask via a double-ended needle. Cool to 0°C and add the zinc(ll) bromide solution. Warm to rt and stir overnight. 

Long wide gauge double-ended needle... 

Long double-ended wide gauge needle... 

In a dry nitrogen flushed 100 ml flask sealed with a septum were placed the phenol (5 mmol) and dry methanol (10 ml). A solution of DIB (1.61 g, 5 mmol) in methanol (25 ml) was transferred via a double-ended needle to the stirred phenolic solution at room temperature over 40 min. After 40 min, the reaction mixture was concentrated and the residue was purified by column chromatography (silica gel, light petroleum to dichloromethane) to afford the title compounds in 65-99% yield. 

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