Amine, diisopropyl

Via the Z-enolate an oven dried Schlenk tube equipped with a rubber septum is flushed with argon and charged with 0.66 mL (1.0 mmol) of butyllithium (1.5 N in hexane). The Schlenk tube is cooled to 0°C (icc/salt) and 0.12 g (1.1 mmol) of diisopropylaminc are added slowly by a syringe. This mixture is stirred for 15 min and the rubber septum is replaced by a glass stopper. The hexane and the excess diisopropyl-amine are removed under reduced pressure. After the flask is filled with argon the stopper is replaced with a septum and 0.47 g (4.3 mmol) of HMPA and 2.5 mL of THF are added. This solution is immediately cooled to — 78 °C and 0.14 g (1.1 mmol) of tert-butyl propanoate arc added quickly by syringe. After stirring for... 

The reaction of diisopropyl sulfide with sulfur monochloride and DABCO afforded l,2-dithiolo-3-thiones 98 and 99 (1999JOC4376). Dithiole ring formation had been assumed to be similar to that produced from tertiary diisopropyl-amines. However, in the case of diisopropyl sulfide only one isopropyl group was... 

Diisopropyl amine was distilled from calcium hydride prior to use. 

An oven-dried, 500-mL, two-necked, round-bottomed flask equipped with a magnetic stirring bar, rubber septum inlet, and an outlet connected to a mercury bu oler is flushed with nitrogen and charged with 100 mL of tetrahydrcruran (THF) (Note 1). To this are added sequentially at 0°C, diIsopropyl amine (Note 2) (10.6 g, 14.7 mL, 105 mmol) and butyllithium in hexane (Note 3) (2.22 M, 47.3 mL, 105 nmol). The reaction mixture is stirred for 30 min and cooled to -78°C. 6-Ionone (Note 4) (19.2 g, 20.3 mL, 100 mmol) is slowly added. After stirring the mixture for 1 hr at -78°C, diethyl chlorophosphate (Note 5) (18.1 g, 15.2 mL, 105 mmol) is added, and the reaction mixture is allowed to warm to room temperature over 2-3 hr (Reaction mixture A) (Note 6). 

Lithium diIsopropyl amide is prepared in a separate 1-L flask from diisopropyl amine (22.8 g, 31.6 mL, 225 mmol), butyllithium in hexane (2.22 M,... 

The submitters used diisopropyl amine (99 ) available from Aldrich Chemical Company, Inc. without further purification. 

Camphor (8) Bicyclor2.2.11heptan-2-one, 1,7,7-tr1methyl- (9) (76-22-2) Lithium diisopropylamide Diisopropyl amine, lithium salt (8) ... 

Secondary amines, such as dimethylamine,10f diethylamine,60 diisopropyl amine,10f dicyclohexylamine,10f A-methylaniline,IOf aziridine,61-63 and azetidine,66 are reported to undergo cis addition to acetylenic esters, giving rise to simple 1 1 Michael adducts, in each case. These adducts have been successfully employed in the synthesis of different heterocyclic compounds. 

On the other hand, if you treat an amine such as diisopropyl amine with n -butyl lithium in tetrahydrofuran (THF), then a different behavior is indicated. In this case the equilibrium lies far to the right so as to be virtually irreversible. The amine therefore functions as an acid and donates a proton to the much stronger base butyl lithium. This is the standard method for the preparation of the versatile base LDA. 

The submitters used ether that had been freshly distilled from sodium and benzophenone under an argon atmosphere. The checkers used anhydrous ether directly from freshly opened 500-g containers from Fisher Scientific Company, Springfield, New Jersey. In addition, the checkers charged the reaction flask with ether using a dry graduated cylinder, flushed the system with argon and then sealed and cooled the vessel to 0°C before the sequential addition of diisopropyl amine and butyllithium. 

Diisopropyl amine from BASF AG, Ludwigshafen, Germany (submitters) and Aldrich Chemical Company, Inc. (checkers) was distilled from calcium hydride, and then stored under argon and over calcium hydride until use. 

SYNTHESIS A solution of 0.50 g 4-acetoxyindole (see under 4-HO-DET for its preparation) in 5 mL Et20 was stirred and cooled to 0 °C with protection from atmospheric moisture. There was then added 0.5 mL oxalyl chloride. The reaction mixture was stirred for an additional 30 min, and the intermediate indoleglyoxyl chloride separated as a yellow crystalline solid but not isolated. This was treated with a 40% solution of diisopropyl amine in anhydrous Et20, dropwise, until the pH was 8-9. The reaction was -----------------------------... 

Diisopropyl amine was distilled, bp 85°C, under a nitrogen atmosphere from calcium hydride immediately prior to use. 

The flask is charged through serum cap B with 17 mL (120 mmol) of diisopropyl amine (Note 3) and 200 raL of tetrahydrofuran (THF) (Note 4), using syringe techniques. It is cooled to -75°C 1n a dry-ice bath. With stirring, exactly 100 mmol of butyl lithium (hexane solution) (Note 5) is introduced from the dropping funnel (Note 6) within 10 min, followed after 0.5 hr, by a... 

Diisopropyl amine was freshly distilled from calcium hydride. 

Homologation of acetylenes to allenes. A one-pot homologation of acetylenes to allenes involves reaction of an acetylenic compound with formaldehyde (1.6 equiv.), diisopropyl amine (1.2 equiv.), and copper(l) bromide at reflux in dioxane or THF (equation I). Other amines and metal salts can be employed, but diisopropylamine and copper(I) bromide give the most satisfactory results (26-97% yields). The reaction is general only for terminal acetylenes and is successful with propargylic alcohols, ethers, and acetates. Racemization is not observed with optically active... 

In addition to their behavior as bases, primary and secondary amines can also act as very weak acids because an N-H proton can be removed by a sufficiently strong base. We ve already seen, for example, how diisopropyl-amine (pK = 40) reacts with butyllithium to yield lithium diisopropylamide (LDA Section 22.6). 

The azaallyl oiolates, Le. enolates derived ftom ketone imines or hydrazones are synthetic equivalents of the ketone enolates and thus two examples of azaallyl enolates are included in this section. Uthiated cyclcdiexationephenylimine (151) crystallizes out of hydrocarbon solution as the dimeric diisopropyl-amine solvate (152). Significant disorder between the cyclohexyl and the phenyl moieties is obse ed in this crystal structure however, it is clear that there are no V-az yl carbon contacts in this structure. This Uthiated imine structure can be compared with the Uthiated diinethylhydrazone of cyclohexanone... 

This simple neutralization reaction always favors the weaker base. Thus the most acidic H is deprotonated, even if the acid has an adjacent CH. Because of the higher electronegativity of heteroatoms, protons on heteroatoms are usually lost before protons on carbon. The base n-butyllithium deprotonates the nitrogen of diisopropyl amine. The adjacent CH is about 14 orders of magnitude less acidic. Always check the eq to be sure your proton transfer is energetically reasonable. The Xgq for the reaction below is highly favorable, 10(50 - 36) = 10+14. 

---