Diisopropyl bromide

A mixture of 84 parts of 3,3-diphenyl-3-cyanopropyl bromide, 41 parts of 4-piperidino4-pi-peridinecarboxamide, 64 parts of sodium carbonate, a small amount of potassium iodide and 1,200 parts of anhydrous toluene was stirred, and heated under reflux for 48 hours. At the end of this time the reaction mixture was allowed to cool to room temperature, and 500 parts of water were added. The resultant precipitate was removed by filtration, and triturated with diisopropyl ether. The crystalline material thus obtained was removed by filtration, and re-crystalli2ed from 320 parts of acetone, to give 1 -(3,3-diphenyl-3-cyanopropyl)4-piperidino-4-piperidinecarboxamide, melting at about 149°C to 150°C. 

Solutions of 7.5 g (40 mmol) of triisopropyl borate in 10 mL of dry diethyl ether and 40 mmol of 0.87 M allylmagnesium bromide in diethyl ether arc added dropwisc separately to 10 mL of diethyl ether at — 78 °C. This mixture is stirred for 0.5 h at —78 JC, then is allowed to warm to r.t. and stirred for 3 h. The slurry is recooled to 0 C. and then 40 mmol or 1 N aq hydrochloric acid saturated with NaCl are added dropwise over 15 min. The mixture is warmed to r.t., and stirring is continued for 10 min. The organic layer is separated and directly treated with 9.4 g (40 mmol) of diisopropyl (/ ,/ )-tartrate (DIPT). The aqueous phase is extracted with three 50-mL portions of diethyl elher/CH.CI, 5 1. The combined organic layers are dried over anhyd MgS04 for 2.5 h, then filtered under argon. The filtrate is concentrated in vacuo and toluene is added to give a final volume of 50 mL. The concentration of reactive allylboronate is determined by treatment of a 1 mL aliquot of this solution with a known excess of cyclohexanecarboxaldehyde. This... 

Stannane 6a underwent facile transmetalation in tetrahydrofuran at — 78 °C on treatment with butyllithium to afford 6b. Addition of the lithium reagent 6b to a solution of 1.1 equivalents of copper(I) bromide-dimethyl sulfide in 1 1 diisopropyl sulfide/tetrahydrofuran at — 78 °C gave the copper reagent 6c, which reacted with methyl vinyl ketone at —78 "C in the presence of boron trifluoride-diethyl ether65, producing 7 in 55% yield65. 

Methoxyphenyl)-2-phenyl-lH-imidazole. A 2-L, three-necked, round-bottomed flask equipped with an addition funnel, reflux condenser, and mechanical stirrer is charged with 500 mL of tetrahydrofuran (THF) and 125 mL of water. Benzamidine hydrochloride monohydrate (50 g, 0.29 mol) (Note 1) is added, followed by the slow, portionwise addition of potassium bicarbonate (54.4 g, 0.57 mol) (Note 2). The reaction mixture is vigorously heated to reflux. A solution of 4-methoxyphenacyl bromide (65.3 g, 0.29 mol) in 325 mL of THF is then added dropwise via the addition funnel over a period of 30 min while the reaction is maintained at reflux. After completion of the addition, the mixture is heated at reflux for 18-20 hr (Note 3), then cooled in an ice bath (Note 4), and THF is removed under reduced pressure using a rotary evaporator. An additional 100 mL of water is added, and the resulting suspension is stirred at 50-60°C for 30 min. The mixture is cooled in an ice bath and the solids are collected by filtration. The filter cake is rinsed with two 100-mL portions of water and air-dried in the filter funnel for 2 hr. The crude product is transferred to a 500-mL flask and 150 mL of diisopropyl ether and 150 mL of hexanes are added. The mixture is stirred for 2 hr at room temperature, and the solids are again collected by filtration. The filter cake is dried in a vacuum oven for 48 hr (68°C/ca. 100 mm) to give 68.6 g (96%) of the desired imidazole as an off-white solid (Notes 5, 6). 

Acetyl bromide cleaves dibenzyl sulfide, while diethyl or diisopropyl are resistant (27). 

Preparation of diisopropyl 2,2-diphenylvinylphosphonate — Reaction of a vinyl bromide with a Cu(I) complex of a trialkyl phosphite74... 

The best compromise with respect to reactivity and availability of the starting material was the use of diisopropyl malate 107. This malic acid ester is easy to prepare and its alkylation with various benzyl bromides can be achieved with good yields (53-67%, not optimized) and high stereoselectivities (dr 95 5 for 120 and 121). An exception with respect to the stereoselectivity was the 2,4,6-trimethylbenzyl substituted succinate 122, which was obtained in a dr of only 83 17 (Fig. 6) [71]. 

Apparently a substantial spacer is also allowable between the aromatic ring and the carboxy group. Gemfibrozi 1 (52), a iiypotriglyceridemic agent which decreases the influx of steroid into the liver, is a clofibrate homologue. It is made readily by lithium diisopropyl amide-promoted alkylation of sodium iso-propionate with alkyl bromide 51. ... 

The chiral, nonracemic, 6-monosubstituted bicyclic lactams 1 are deprotonated by a strong base (usually lithium diisopropyl amide) and then alkylated with an iodoalkane or an allylic or benzylic bromide. Alkylation preferentially takes place from the side opposite to that of the substituent R1, which is usually an alkyl or an aryl group. While the diastereomeric ratios may be as low as 75 25, they are most often >90 10 (see Table 9). The minor diastereomer can in most cases be easily removed by liquid chromatography and/or recrystallization to yield the pure major diastereomer. 

Bei der Reaktion von Diisopropylamin mit l-Chlor-2,4-dinitro-benzol in Benzol bei 60° entsteht das erwartete N,N-Diisopropyl-2,4-dinitro-anilin nur in sehr geringer Ausbeute als Hauptprodukt entsteht das nur eine Isopropyl-Gruppe enthaltende 2,4-Dinitro-N-iso-propyl-anilin neben einer geringeren Menge an 2,4-Dinitro-N propyl-anilin1. Ahnliche Er-gebnisse erhalt man mit dem entsprechenden Aryl-fluorid und -bromid sowie bei Durch-fiihrung der Reaktion in Methanol oder Dimethyl-sulfoxid. 

When the alcohol adduct from the allenylzinc reagent and diisopropyl ketone was treated with 80 mol% of allenylzinc bromide in HMPA, a mixture containing 12% of diisopropyl ketone and 88% of recovered alcohol was obtained after 7 days at ambient temperatures (equation 1). Thus, it may be deduced that the allenylzinc additions are reversible. Presumably, the propargyl adducts are intrinsically favored, but steric interactions between the R1 and R2 substituents in the propargyl product favors an increased proportion of allenyl adducts in a reversible process (see Table 1). HMPA would expectedly facilitate reversal of the addition by decreasing the ion pairing between the alkoxide anion and ZnBr cation of the adducts. This expectation was subsequently confirmed by a study of solvent effects. 

An alternate synthesis is outlined in Scheme 2.1 2 Diisopropyl dichloromethylboronate (6) is readily prepared by reacting triisopropyl borate with dichloromethyllithium prepared in situ. 20 Transesterification with a suitable C2 symmetric diol gives an ester 7 that can be treated with an alkylmagnesium bromide to yield chloride 8 and then, after transesterification with pinanediol (see Section 15.1.7.2) a product 9 which is analogous to 3. 

In this method, the bromide ion is converted to 2-bromoethanol by reaction with ethylene oxide in acetonitrile diisopropyl ether under acidic conditions. The 2-bromoethanol thus produced is determined by gas chromatography using an electron capture detector. 

The (E) and (Z) forms of the vinylboron compounds 278 and 279 can be prepared by hydroboration of alkynes and haloalkynes, and their reactions with the (E)- or (Z)-vinyl iodides or bromides 280 and 281 proceed without isomerization the four possible isomers 282-285 can be prepared in high purity. However, for the efficient preparation of the (Z,Z)-dienes 287, the diisopropyl ester of (Z)-alkenylboronic acid 286 should be used. Other boron compounds give poor yields... 

We applied these optimized conditions with aryl bromide 38. Bromide 38 was prepared from isophthalic acid by bromination in the meta position with concentrated sulfuric acid, bromine and silver sulfate to give compound 37,34 which was converted to the isopropyl ester with HMPA and isopropyl iodide (Scheme 14). When 5-bromo-isophthalic acid diisopropyl ester 38 was treated with diphenethylamine only starting material and reduced aryl compound... 

As mentioned in Section 9.12.2.1.1, the boron-zinc exchange can be performed stereoselectively if diisopropyl-zinc instead of diethylzinc is used. For example, hydroboration of the chiral, racemic endocyclic olefin 134 with diethylzinc, followed by twofold transmetallation and electrophilic capture of the resulting copper intermediate with allyl bromide was used for the highly diastereoselective formation of the stereotriad in product 136 (Scheme 35).35,35a 103 QorreSp0nding enantioselective transformations were carried out with chiral boranes and catalytic amounts of copper salts (see Section 9.12.2.2.2).36... 

Diisopropyl Ditellurium [Sodium Hydride Method]2 A 500 ml flask fitted with a magentic stirrer and a reflux condenser is purged with nitrogen and charged with 15.0g (0.11 mol) of tellurium and 100 m/ of dimethylformamide (freshly distilled from calcium chloride). 5.64 g of a 50% suspension of sodium hydride (0.11 mol) in mineral oil are added, the mixture is slowly heated over 1 h to 70° with stirring on a water bath, maintained at this temperature for 3 h, and then allowed to cool to 20°. 14.50 g (0.11 mol) of isopropyl bromide are added dropwise over 30 min, the mixture is stirred for 30 min, poured into 200 ml of water, and extracted with three 25 ml portions of chloroform. The combined extracts are washed with three 25 ml portions of distilled water, dried with anhydrous calcium chloride, and the solvent removed under aspirator vacuum. The residue is purified by chromatography on silica gel with hexane as the mobile phase yield 13.5 g (72%) b.p. 92°/2 torr. 

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... 

ALDOL CONDENSATION (+)-(R)-l-Amino-2- methoxymethyl)pyrrolidine. Boron trichloride. Dialkylboron tri-fluoromethanesulfonates. Dibenzyl-ammonium trifluoroacetate. Di- -butylboryl trifluoromethanesulfonate. Dichlorodiethylaminoborane. Diiso-propylaluminum phenoxide. Diisopropyl-aminomagnesium bromide. Lithium diisopropylamide. Morpholine-Camphoric acid. Proline. 

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