One-step procedure

Most polyimides are insoluble in organic solvents, but some are soluble. Soluble polyimides can be synthesized in one-step (Eq. 2) [17-22]. The polyimide solution is obtained by reacting a diamine with a tetracarboxylic dianhydride in a high boiling point solvents (phenolic solvent, for example, wi-cresol) at 150-200°C. As the polyamic acid is formed and converted to the polyimide in solution, the water formed during imidation is removed as an azeotrope with toluene to obtain high molecular weight polyimide. 

It was reported that the molecular weights of polyimides prepared in one-step procedure were higher than those of polyimides prepared in two-step procedure [21] and the polyimides prepared in one-step procedure showed higher strength than those prepared in two-step procedure [18], and the one-step procedure is thought to be more suitable for the synthesis of soluble polyimides. The solubility of some polyimides prepared by the one-step procedure was reported to be higher than that of polyimides prepared by two-step procedure in spite of the same structures [22]. Thermoplastic polyimides and polyimide adhesives are prepared by this method. 

Synthesis using tetracarboxylic dithioanhydrides [26,27] instead of tetracarboxylic dianhydrides and the high-pressure synthesis from nylon-salt-type monomers composed of diamines and tetracarboxylic acids [28-32] have also been reported. 

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A very direct, one-step procedure for the preparation of a particular 6a-methoxy-penicillanate, which also presumably goes through a 6-acylimino intermediate, has been described (Scheme 47) (81AG(E)808). Note that this route does not even require blocking of the 3-carboxyl. 

The present method is a simple, one-step procedure employing commercially available or readily accessible starting materials. Other a-nitro carboxylic esters may be prepared in this way for example, dimethyl 2-nitropentanedioate was prepared in 45-50% yield,... 

In general, this method is a one-step procedure for the oxidation of a cresol type of molecule to the corresponding phenolic acid. The vigorous reaction conditions clearly limit the type of functional groups that may be present in the molecule. There is no evidence that the reaction has been applied to polynuclear or heterocyclic alkylphenols. 

An affinity sorbent based on WPA-PG carrying immobilized human IgG was applied to the isolation of the first component of the complement (Cl) from human serum and for its separation into subcomponents Clr, Cls and Clq by the one-step procedure [126,127]. Cl was quantitatively bound to the sorbent at 0 °C. The activities of subcomponents Clq and Clr2r2 in the unbound part of the serum were found to be 0.8% and 3.3% of the initial activities in serum. This fraction, therefore, could be used as a R1 reagent for determining the hemolytic activity of Cl. Apparently, the neighboring macromolecules of immobilized IgG resemble to some extent an immune complex, whereas Cl formation is facilitated due to the mobility of polymer chains with the attached IgG macromolecules (Cl is usually dissociated in serum by 30%). After activation of bound Cl by heating (30 °C, 40 min) the activated subcomponent Clr is eluted from the sorbent. Stepwise elution with 0.05 mol/1 EDTA at pH 7.4 or with 0.05 mol/1 EDTA + 1 mol/1 NaCl at pH 8.5 results in a selective and quantitative elution of the activated subcomponent Cls and subcomponent Clq. 

The present one-step procedure for preparation of 5,6-dihydro-2if-pyran-2-one is slightly modified from that described in the original paper.9 It is simpler and easier than the three-step method3 used in the past and represents the most convenient synthesis presently available. The present preparation of 2f/-pyran-2-one has several advantages compared to the alternatives mentioned above simplicity of apparatus and technique, mild reaction conditions, availability of reactants, and ease of product isolation. 

The new reaction appears to be a simple one-step procedure, which is particularly suitable for tertiary alkyl-aryldiazenes for which alternative synthetic routes are less convenient. However, aryl radicals or alkyl radicals in which the carbon-centered radical is bonded to an electron-withdrawing group (COOR, COR, CONR2, CN, S02R, etc.) do not add to diazonium salts or give only poor results (Citterio et al., 1982 c). This indicates that the radical must be a relatively strong nucleophile in order to be able to react with a diazonium ion. 

Racemic or optically active /J-disulphoxides can be obtained via a facile one-step procedure from arenesulphinic esters and a-sulphinyl carbanions558 or by oxidation of a-sulphinyl carbanions559. 

The present one-step procedure for making 4-methylpyrimidine is simpler and easier than the three-step method used in the past. The present procedure and modifications of it have been used to make a variety of 4- and 4,6-substituted pyrimidines.2 8... 

Fourier transform infrared (FTIR) spectroscopy (NaCl) shows no remaining carboxylic acid (1696 cm-1, carbonyl) but only ester groups (1736 cm 1, carbonyl) Mn(SEC) = 6530 Mn(1H NMR) = 1640 theory for third generation Mn = 2570.65 Polyesters of higher generation were synthesized according to this pseudo-one-step procedure and were analyzed by SEC, VPO, and 111 NMR.65... 

Attempts have been made to incorporate functional groups into the phosphonates in zinc phosphonate structures. Zn(03P(CH2)2C02H) H20 was reacted with aromatic amines but no amide formation was observed. However, Zn(03P(CH2)2C0NHC6H5) could be synthesized directly from zinc nitrate, (2-carboxyethyl)phosphonic acid, and aniline in a one-step procedure.406... 

The solution procedure for the second problem is a one step procedure in which the problem is solved considering both central storage and inherent storage. The central storage vessel in this case has a fixed size. The objective used is dependent on whether the required production is known or not. If the required production is known then the objective is the minimisation of effluent. If this is not known then the objective is the maximisation of profit. 

The initial synthesis and resolution of 88 was performed as a one-step procedure with the resolving agent added to the reaction mixture after addition of PCI5 <1997AGE608>. An improved two-step procedure enabled the scale-up of the reaction from a 100mg scale to a 40g scale <1998TL4825, 2004JOC8521>. 

Elastomers Prepared. The three elastomers discussed herein were prepared from PPG, toluene-2,4-diisocyanate (TDI), and either LHT-240 or TIPA. Elastomers prepared by a one-step procedure are designated LHT-240 and TIPA, indicative of the triol used. A third elastomer, designated Tri-NCO, was prepared by first reacting LHT-240 with all of the required TDI for two hours at 50°C to obtain a triisocyanate (or essentially... 

The bioluminescent determinations of ethanol, sorbitol, L-lactate and oxaloacetate have been performed with coupled enzymatic systems involving the specific suitable enzymes (Figure 5). The ethanol, sorbitol and lactate assays involved the enzymatic oxidation of these substrates with the concomitant reduction of NAD+ in NADH, which is in turn reoxidized by the bioluminescence bacterial system. Thus, the assay of these compounds could be performed in a one-step procedure, in the presence of NAD+ in excess. Conversely, the oxaloacetate measurement involved the simultaneous consumption of NADH by malate dehydrogenase and bacterial oxidoreductase and was therefore conducted in two steps. 

It was found by Trost that the low reactivity could be circumvented by the employment of labile ligands, such as the propionitrile in the Mo(CO)3(EtCN)3 precatalyst [57]. Instead of directly transferring this procedure to microwave heating applications, a useful and easily handled microwave procedure was developed for rapid and selective molybdenum-catalyzed allylic alkylations under noninert conditions (Eq. 11.39) [12]. The former, more sensitive, two-step reaction was fine-tuned into a robust one-step procedure employing the inexpensive and stable precatalyst Mo(CO)6, used in low concentrations. The alkylations were conducted in air and resulted in complete conversions, high yields, and an impressive enantiomeric excess (98%) in only 5-6 min. Despite the daunting temperatures, up to 250°C with THF... 

In order to be able to isolate both PS1 and PS2 from the thermophilic cyanobacterium Thermosynechococcus elongatus by a one-step procedure and in order to immobilize both photosystems on the surface of the support materials (i.e. the electrodes) in an oriented... 

This one-step procedure is a convenient and general method for the preparation of carbamates. It is substantially simpler, quicker, and safer than the multistep methods hitherto used for the preparation of carbamates of tertiary alcohols. This procedure is applicable to the preparation of carbamates of primary, secondary, and tertiary alcohols and mercaptans, polyhydric alcohols, acetylenic alcohols, phenols, and oximes. It has also been extended to the preparation of carbamyl derivatives (i.e., ureas) of inert (non-basic) amines.10... 

An alternative one-step procedure involving treatment of the enediynyl propargylic alcohols 14a and 14b with triphenylphosphine, DEAD and finally o-nitro-benzenesulfonylhydrazine to give the corresponding enyne-allenes 15a and 15b, respectively, under mild thermal conditions has also been reported (Scheme 20.5)... 

ChIoro-4-hydroxyquinoline was prepared in 91-93% yields in a one-step procedure, when N-(3-chlorophenyl)aminomethylenemalonate (250) was heated in boiling Dowtherm A for 0.5-2 hr, and the reaction mixture was then treated with water at the same temperature for 1-2 hr (73MIP2). 

Since the advent of the one step procedure for the preparation of various substituted thenaldehydes (44), the majority of the necessary starting materials were readily available. Consequently, the Reformatsky reaction was studied with these compounds. With the a-bromoesters the reaction was successfully carried out with four of the thenaldehydes and 2-acetothienone. The nature of the product seemed to depend on the degree of branching of the bromoester. In only one case, where ethyl bromoacetate was used, was a hydroxyester obtained. However, when the carbon atom adjacent to the carbethoxy group was substituted, the product usually contained a hydroxyl group. The dehydration by means of aqueous oxalic acid resulted in a nearly quantitative conversion to the unsaturated esters. 

A practical, inexpensive one-step procedure was developed for the RhaD-catalyzed gram-scale synthesis of L-fructose. The requirement for DHAP as the donor substrate was circumvented by use of borate buffer, presumably by in situ formation of borate esters as a phosphate ester mimic. Racemic glyceraldehyde was also used, as the enzyme preferentially accepted the L-enantiomer as a substrate. The method can also be apphed to other products, including L-rhamnulose, and towards a two-step synthesis of L-iminocychtols. ... 

We have been able to develop a one-step procedure (14) for the preparation of LAGA by acid catalyzed dehydration directly from gluconic acid or from its 1,4- or... 

F-Labelled 2-amino-2 -fluorobenzhydrol, intermediates in the synthesis of amino benzodiazepinones, has been synthesized in an elegant one-step procedure [168] based on the specific ortho coupling of an anilinodichloroborane with an aldehyde [169] (Scheme 32). 

Dixon [75] also investigated the use of unconventional carbon donors, such as the mandelic acid derivative 119 in the highly stereoselective addition to -substituted nitro-olefms. The Michael product 120 was formed smoothly and can be converted in simple one-step procedures to generate various chiral building blocks for syntheses (Scheme 26). 

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