New Methods for the Synthesis

In 1971, Batcho and Leimgruber introduced a new method for the synthesis of indoles. For example, condensation of o-nitrotoluene (5) with N,N-dimethylformamide dimethyl acetal (6) (DMFDMA) was followed by reduction of the rrans-P-dimethylamino-2-nitrostyrene (7) which resulted to provide the indole (8). ... 

Raney nickel desulfurization of the macrocyclic ketones or their reduction products confirmed the structures assigned to these compounds and simultaneously offers new methods for the synthesis of macrocyclic alicyclic compounds. =°... 

Several new methods for the synthesis of 1,5-diones were described recently,Although some methods to be discussed further (e.g., type in Section II,C, 2,g) obviate the necessity of preparing... 

With the development of new teehnologies and industrial fine synthesis, the importanee of produets from diaeetylene as unique building bloeks, synthons, and monomers will inerease. And it is the small-seale produetion of diaeetylene-based heteroeyelie reagents that may beeome the first step in the proper industrial utilization of diaeetylene. This will provide a base for launehing new methods for the synthesis of a large number of valuable heteroeyelie eompounds that are still inaeeessible from eheap industrial feedstoek (00UK642). 

A new method for the synthesis of 1,2,5-thiadiazoline 5,5-dioxides 231 was achieved by reacting activated aryl nucleophiles to the C=N double bond of the corresponding thiadiazoles 230 in the presence of AlClj as a catalyst at room temperature (00MI4). The yields of 4-aryl-derivatives ranged from 38 to 92%. 

Evans developed a new method for the synthesis of [(-C-allylglycosides, based on BusSnOTf-mediated ring-opening of glycal epoxides with allylstannanes as nucleophiles [81a], This methodology has been efficiently used in the (3-stereoselective introduction of the side chain (C44-C51) of spongistatin 2 (Scheme 8.43) [81b,c]. 

New Methods for the Synthesis of 2-Amino-2-deoxyglucosides Utilizing N-2, 4-Dinitrophenyl (DNP) Derivatives. P. F. Lloyd and M. Stacey, Chem. Ind. (London), (1955) 917. 

The wide choice of new methods for the synthesis of P-chirogenic phosphines can be appreciated from the above results,. The synthetic description of this chapter ends here and gives place to the great catalytic potential of these ligands. 

Phenol is the starting material for numerous intermediates and finished products. About 90% of the worldwide production of phenol is by Hock process (cumene oxidation process) and the rest by toluene oxidation process. Both the commercial processes for phenol production are multi step processes and thereby inherently unclean [1]. Therefore, there is need for a cleaner production method for phenol, which is economically and environmentally viable. There is great interest amongst researchers to develop a new method for the synthesis of phenol in a one step process [2]. Activated carbon materials, which have large surface areas, have been used as adsorbents, catalysts and catalyst supports [3,4], Activated carbons also have favorable hydrophobicity/ hydrophilicity, which make them suitable for the benzene hydroxylation. Transition metals have been widely used as catalytically active materials for the oxidation/hydroxylation of various aromatic compounds. 

In conclusion, we have been successful in developing a new method for the synthesis of [ 1,2,3]-triazoles by regioselective 1,3-dipolar cycloaddition of 2-diazopropane with imidates 60 in good yields. 

As already described for the all-carbon-Diels-Alder reaction, a hetero-Diels-Alder reaction can also be followed by a retro-hetero-Diels-Alder reaction. This type of process, which has long been known, is especially useful for the synthesis of heterocyclic compounds. Sanchez and coworkers described the synthesis of 2-aminopyridines [48] and 2-glycosylaminopyridines 4-144 [49] by a hetero-Diels-Alder reaction of pyrimidines as 4-143 with dimethyl acetylenedicarboxylate followed by extrusion of methyl isocyanate to give the desired compounds (Scheme 4.30). This approach represents a new method for the synthesis of 2-aminopyridine nucleoside analogues. In addition to the pyridines 4-144, small amounts of pyrimidine derivatives are formed by a Michael-type addition. 

Quinoline derivatives are of major interest as bioactive compounds. A new method for the synthesis of polycyclic fused quinolines 4-207 was developed by Rossi and coworkers [71], who used the [2+2] cycloaddition of an alkyne 4-204 with enamines 4-205 to give 4-206 (Scheme 4.45). Thereby follows an annulation, with the formation of 4-207a-c. 

Narayanan N, Strekowski L, Lipowska M, Patonay G (1995) A new method for the synthesis of heptamethine cyanine dyes synthesis of new near infrared fluorescent labels. J Org Chem 60 2391-2395... 

Several new methods for the synthesis of the oxazole nucleus were published. A new consecutive three-component oxazole synthesis by an amidation-coupling-cycloisomerisation sequence was developed. The synthesis started from propargylamine 92 and acyl chlorides. To extend this process, a four component sequence involving a carbonylative arylation by substitution of one acyl chloride with an aryl iodide and a CO atmosphere was also performed <06CC4817>. 

A new method for the synthesis of 1,2,3-thiadiazoles has been reported. The method starts with the thioanilide derivative 72, which is converted into the hydrazone 73. Oxidative heterocyclization by treatment with hydrogen peroxide gave exclusively the 1,2,3-thiadiazoline 74 (Scheme 8) <2003S2559>. 

The thermodynamic data presented in Table XYI are calculated for the temperature T=0K. Note that the entropy factor favors betaine decomposition via directions A and B at higher temperatures. The reactions of organoelement analogs of carbenes with phosphorus and arsenic ylides are yet poorly studied. The presented above results of calculations allow an optimistic prognosis about the possibility of developing a new method for the synthesis of elementaolefins R2E14=CH2 (E14 = Si, Ge, Sn) on the basis of these reactions. 

Recognizing that intermediates in the [4 + 2]-reaction of dienes and alkynes could be intercepted with components in addition to CO as in the [4 + 2 + l]-reaction, Gilbertson and Evans independently published two new methods for the synthesis of eight-membered carbocycles involving [4 + 2 + 2]-cycloadditions. Saa and co-workers report a... 

Triazolo[4,3-7 ]pyridazinc-6(5//)-one-3(2//)-thiones 309 undergo an unprecedented ring transformation on treatment with dimethyl acetylenedicarboxylate in DMF, resulting in a new method for the synthesis of thiazolo[2,3-c][l,2,4]triazole derivatives, which is strongly dependent on the reaction temperature and the... 

New approaches have been found for cyclization to [l,2,3]triazolo[l,5- ]pyrimidine (41) <2006JHC1563> and [l,2,4]triazolo[l,5-tf]pyrimidine (42) <2005RCB2903> both ring closure reactions started from the appropriate aminotriazoles. A new method for the synthesis of [l,2,4]triazolo[4,3-tf] quinoxalines (derivatives of the benzologue of ring system 37) has also been reported <2006SC1873>. 

Since the field was last reviewed,1 a number of linear and cyclic oligogermanes have been reported, as have a number of new methods for the synthesis of polygermanes. The Ge-Ge single bond length is typically considered to be approximately 2.45 A, which is twice the atomic radius of germanium. 

W Konig, R Geiger. A new method for the synthesis of peptides activation of the carboxyl group with dicyclohexylcarbodiimide and 1-hydroxybenzotriazoles. Chem Ber 103, 788, 1970. 

K Kaljuste, A Unden. New method for the synthesis of V-methylamino acids containing peptides by reductive methylation of amino groups on the solid phase. Int J Pept Prot Res 42, 118, 1993. 

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