Typical Reaction Procedure

7 Intramolecular CycMzatlons and Conjugate Additions Mediated by Rieke Zinc 

Active zinc is an effective mediator in intramolecular conjugate additions [49]. For example, a spirodecanone was formed from the 1,4-addition of the organozinc reagent, which was readily available from the primary iodide (Equation 3.2) [50]. Other types of ring closures also occur (Equations 3.3 and 3.4), 

8 The Formation and Chemistry of Secondary and Tertiary Aikylzinc Halides 

A representative procedure to a slurry of Rieke zinc (7.98 mmol) in THF (25 ml) under argon was added 2-bromobutane (7.95 mmol), and the mbcture was refluxed for 2.5 h. The resulting light brown solution was cooled to rt and was transferred via cannula to a THF (10 ml) solution of CuCN (1.5 mmol) and LiBr (1.5 mmol) at -45°C. Benzoyl chloride (7.95 mmol) was added neat, and the mixture was warmed slowly to rt over 4h. The reaction mbcture vras quenched with 3M HCl (20 ml) and extracted with ether (3 x 20 ml), and the combined organic layers were washed with water (20 ml), dried over MgS04, and concentrated. 2-Methyl-l-phenylbutanone (7.52 mmol, 95%) was isolated from the crude reaction mixture by flash chromatography (hexanes/ethyl acetate). 

Enones A, ethyl 6-methyl-2-oxo-3-cyclohexene-l-carboxylate B, 3-penten-2-one  

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Typical reaction procedure is as follows biphenyl (25 mmol), propene (50 mmol), HM (1 g), and trans-decalln (20 cm ) were heated in an autoclave at 200°-300°C for 4 h. Products were analyzed by a Hewlett-Packard Gas-chromatograph Model 5890 equipped with a 25 m capillary column of Ultra-1. 

A typical reaction procedure was as follows. 10.0 mmol of olefin, 10.0 mmol of oxidant and 10 ml of solvent were charged into a 50 ml three-necked glass reactor equipped with a condenser and a magnetic stirrer. 50 mg of catalyst was added and the mixture was stirred at 60°C. Analysis was performed by gas chromatograph (column OV-1 bonded 0.25mm X 50 m). 

A typical reaction procedure was as follows a mixture of zeolite (5 g) and amide (10 mmol) in an appropriate solvent (25 ml) was vigorously stirred under reflux at 75°C (using a thermostated bath) under nitrogen atmosphere. The reaction was periodically monitored by GLC. At the end of the reaction, the mixture was filtered and the cake washed with methanol and diethyl ether. After drying with anhydrous sodium sulfate, the solvent was evaporated and the residue purified by distillation or crystallization. The known compounds were characterized by their GC/MS spectra, as well as by their melting points or boiling points, by comparison with standards. 

Preparative Methods readily prepared from the reaction of PhMe2SiCl with 2 equiv of Li metal in THF or from the reaction of PhMe2SiSiMe2Ph with Li metal in THF. Typical reaction procedure involves stirring chlorodimethylphenyl-silane with lithium in THF at 0 °C under N2 for 4—36 h the chlorosilane is converted into tetramethyldiphenyldisilane in the first 10 min, and the remainder of the time is needed to cleave the disilane. The supernatant reagent solution is calibrated using standard methods and used without further purification for reactions. It is sometimes advantageous to activate the Li metal prior to use by ultrasound irradiation of a hexane suspension, and to use argon as the inert gas to prevent formation of lithium nitrides. 

A typical reaction procedure is desoibed in the following (see Scheme 6.3). The step growth polymerization of SPTES copolymers with endcapping group was carried out in a 250 ml three-neck round-bottom flask equipped with a mechanical stirrer and a nitrogen inlet-outlet. 3,3 -Disulfonate-4,4 -difluorodiphenylsulfone (4.5833 g. 

In a typical Knof procedure, 3jS-hydroxyandrost-5-en-17-one acetate is epoxidized with perbenzoic acid (or m-chloroperbenzoic acid ) to a mixture of 5a,6a- and 5)5,6)5-epoxides (75) in 99 % yield. Subsequent oxidation with aqueous chromium trioxide in methyl ethyl ketone affords the 5a-hydroxy-6-ketone (76) in 89% yield. Baeyer-Villiger oxidation of the hydroxy ketone (76) with perbenzoic acid (or w-chloroperbenzoic acid ) gives keto acid (77) in 96% yield as a complex with benzoic acid. The benzoic acid can be removed by sublimation or, more conveniently, by treating the complex with benzoyl chloride and pyridine to give the easily isolated )5-lactone (70) in 40% yield. As described in section III-A, pyrolysis of j5-lactone (70) affords A -B-norsteroid (71). Knof used this reaction sequence to prepare 3)5-hydroxy-B-norandrost-5-en-17-one acetate, B-noran-... 

In the following, after a brief description of the experimental setup and procedures (Section 13.2), we will first focus on the adsorption and on the coverage and composition of the adlayer resulting from adsorption of the respective Cj molecules at a potential in the Hup range as determined by adsorbate stripping experiments (Section 13.3.1). Section 13.3.2 deals with bulk oxidation of the respective reactants and the contribution of the different reaction products to the total reaction current under continuous electrolyte flow, first in potentiodynamic experiments and then in potentiostatic reaction transients, after stepping the potential from 0.16 to 0.6 V, which was chosen as a typical reaction potential. The results are discussed in terms of a mechanism in which, for methanol and formaldehyde oxidation, the commonly used dual-pathway mechanism is extended by the possibility that reaction intermediates can desorb as incomplete oxidation products and also re-adsorb for further oxidation (for the formic acid oxidation mechanism, see [Samjeske and Osawa, 2005 Chen et al., 2006a, b Miki et al., 2004]). 

The oxidation reactions were performed in a 25 mL ronnd bottom flask. In a typical reaction the catalyst (0.5 % Fe mol) was added to 0.125 M olefin solntion in acetone then dry TBHP (3.5 M in CH2CI2 or in PhCl) was added in one step, and the reaction mixture was stirred and heated in an oil bath at 40°C for 7 h. For the allyhc oxidation of cyclohexene with isotopically labelled oxygen ( 02) the following procedure was carried out the suspension of the catalyst (0.5% Fe mol) in cyclohexene (4 mL, 0.125 M) was frozen and the air in the reactor was evacuated and replaced by an oxygen (21% mol) - argon (79% mol) mixture. Then, the suspension was allowed to warm at room temperatnre and 1.3 mmol of degasified TBHP was added to the solution and the reaction mixtnre was stirred at 40°C for 3 h. 

Scheme 2.18 gives some representative olefination reactions of phosphonate anions. Entry 1 represents a typical preparative procedure. Entry 2 involves formation of a 2,4-dienoate ester using an a, 3-unsaturated aldehyde. Diethyl benzylphosphonate can be used in the Wadsworth-Emmons reaction, as illustrated by Entry 3. Entries 4 to 6 show other anion-stabilizing groups. Intramolecular reactions can be used to prepare cycloalkenes.264... 

A solvent-free synthesis of substituted spiroindolinonaphth[2,l-fo][l,4]oxazines through condensation of 2-methylene-l,3,3-trimethylindoline derivatives with 1-nitroso-2-naphthol under microwave irradiation has been described by Fedorova and colleagues (Scheme 6.263) [453], In a typical reaction, an equimolar mixture of the two starting materials was irradiated at 65-110 °C for 15 min to produce the desired spiroindolinonaphth[2,l-fo][l,4]oxazines, which are useful as photochromic compounds. In a related procedure, addition of morpholine to the reaction mixture led to the formation of the corresponding 6 -amino-functionalized spiroindolino-naphth[2,l-fo][l,4]oxazines, which exhibit a strong hypsochromic color shift (not shown) [453]. 

Several procedures for the synthesis of calcitriol have been reported in the literature. Parren et Uskokovic and others (10-18) have described lengthier syntheses utilizing more readily available starting materials. A typical reaction scheme, utilizing 1 a, 25-diacetoxy-7-dehydrocholesterol as the starting material, is shown in Figure 6. 

A typical condensation procedure involves a one-step reaction where the monomer and suitable catalyst/initiator are mixed and heated to the required reaction temperature. To accomplish a satisfactory conversion, the low molar mass condensation products formed throughout the reaction have to be removed. This is most often accomplished by using a flow of inert gas and/or by reducing the pressure in the reaction vessel. The resulting polymer is generally used without any purification or, in some cases, after precipitation of the dissolved reaction product from a nonsolvent. 

On the other hand, the method of Mukaiyama can be succesfully applied to silyl enol ethers of acetic and propionic acid derivatives. For example, perfect stereochemical control is attained in the reaction of silyl enol ether of 5-ethyl propanethioate with several aldehydes including aromatic, aliphatic and a,j5-unsaturated aldehydes, with syir.anti ratios of 100 0 and an ee >98%, provided that a polar solvent, such as propionitrile, and the "slow addition procedure " are used. Thus, a typical experimental procedure is as follows [32e] to a solution of tin(II) triflate (0.08 mmol, 20 mol%) in propionitrile (1 ml) was added (5)-l-methyl-2-[(iV-l-naphthylamino)methyl]pyrrolidine (97b. 0.088 mmol) in propionitrile (1 ml). The mixture was cooled at -78 °C, then a mixture of silyl enol ether of 5-ethyl propanethioate (99, 0.44 mmol) and an aldehyde (0.4 mmol) was slowly added to this solution over a period of 3 h, and the mixture stirred for a further 2 h. After work-up the aldol adduct was isolated as the corresponding trimethylsilyl ether. Most probably the catalytic cycle is that shown in Scheme 9.30. 

The automatic procedure for time-series reference spectra generation was first demonstrated for the homogeneous catalyzed rhodium hydroformylation of cyclo-octene using Rh4(CO)i2 as precursor, n-hexane as solvent and FTIR as the in situ spectroscopy at 298 K [64]. Upon addition of hydrogen to the system, hydroformylation is initiated. A typical reaction spectrum (k=7) and the pre-conditioned... 

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