Multigram synthesis

This is the basis of a generally applicable multigram synthesis routes to isolable 1-10 nm organosols of the transition metals that are easily redispersible in high concentration in organic phases (Figure 7) [3,183]. 

Microwave-assisted Heck reactions have also been carried out with triflates as coupling partners, involving some very complex molecules. Winterfeld and coworkers have reported a multigram synthesis of a complex non-symmetrical bis-steroidal diene by microwave-promoted coupling of the corresponding alkene and triflate steroidal moieties (Scheme 6.8) [27]. 

The Raillard group at Affymax developed a multigram synthesis of a 2,5-diketopiperazine and other heterocyclic systems by employing a high-load Merri-field resin transformed into polymer-supported valine, which was used as the amino component in an Ugi-4CR to gave the target diketopiperazine 137 after cleavage of 136 from the resin [77] (Scheme 2.49). 

As a final test of the system a scaled reaction was performed, producing 9.34 g (40.8 mmol) of 31 with a catalyst loading of 182 mg Pd EnCat (equating to 0.2 mol% palladium), demonstrating that this system is applicable to multigram synthesis. 

Oxidative cyclizations of dienes and polyenes mediated by transition-metal-oxo species to yield tetrahydrofurans and tetrahydropyrans have been reviewed by Piccially <2007S2585>. A multigram synthesis of diastereomerically pure tetrahydrofuran diols that applies the oxidation of 1,5-dienes has been published <2007S2751>. 

Eguchi, T. Morita, M., and Kakinuma, K., Multigram synthesis of mevalonolactone-rf, and its application to stereochemical analysis by H NMR of the saturation reaction in the biosynthesis of the 2,3-di-O-phytanyl-5 -glycerol core of the Archaeal membrane lipid, 7. Am. Chem. Soc., 120, 5427, 1998. 

The synthesis protocols shown in Schemes 15—19 afforded access to 10—100 mg quantities of some of the procyanidins shown, permitting assessment of their in vitro biological activities. " With a view to fully develop the potential clinical applications for this class of compounds, and to address pharmacological and toxicological requirements, Romanczyk and coworkers recently reported the process scale-up conditions required for the multigram synthesis of procyanidin B-1 (90) and the 3,3-di-O-gallate (98) of procyanidin B-2... 

Cycloaddition of ethyl vinyl ether to the 3,6-tetrazinedicarboxylic acid disodium salt has been developed as an efficient multigram synthesis of 3,6-pyridazinedicarboxylic acid (Scheme 109). A key feature of this process is that the otherwise facile decarboxylation reactions of acids are minimized by use of their sodium salts, and if required the free acid is obtained by ion exchange <87JHC1285>. 

Because preliminary tests of 6 and 7 in catalytic reactions showed the superior activity of 7, we realized the convenience of synthesizing 7 without the need to isolate the (IPr)Pd(acac)2 intermediate. A one-pot, multigram synthesis of 7 is summarized in Scheme 14.6. Reaction of the free carbene IPr with Pd(acac)2 in anhydrous 1,4-dioxane at room temperature, followed by the addition of an equimolecular amount of HCl, leads to the formation of the desired product. An improved synthesis of 7 was recently developed. With this protocol, isolation of the carbene is no longer required, and the complex can be directly prepared from commercial sources in excellent yields (Scheme 14.7). 

An attempt to develop a multigram synthesis of458 provoked a reinvestigation of aryne generation from polyhalobenzenes k The main results are the following. Hexabromobenzene, BuLi (1 equiv) and furan give monoadduct 460 via 3,4,5,6-tetrabromobenzyne further metallation occurs at the 2-Br (and with 2 equiv of BuLi, at the 2,3-bromines, as established by low-temperature proton quenching) and elimination... 

Convenient multigram synthesis of monodisperse oligo(ethylene glycols) effective reaction monitoring by infrared spectroscopy using an attenuated total reflection fibre optic ptrobe. Tetrahedron Letters Vol.50, pp. 6469-6471, ISSN 0040-4039... 

Owing to the usefulness of 1,1 -diaminoferrocene as a building block, we report here its convenient multigram synthesis by a modified Nesmeyanov protocol. In addition, l,l -dibromoferrocene, the first intermediate in the process, is a valuable precursor in its own right, and we also provide a convenient route to multigram... 

Multigram Synthesis of an Atorvastatin Intermediate 48 Using a Mutant Halohydrin Dehalogenase... 

Multigram synthesis of an atorvastatin intermediate 48 using a mutant halohydrin dehalogenase [81]. 

Gelves, G.A., Murakami Zakari, T,M Krantz, M.J. and Haber, J.A. (2005) Multigram synthesis of copper nanowires using ac electrodeposition into porous aluminium oxide templates. Journal of Materials Chemistry, 16, 3075-83. 

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