Sodium carbonate , as base

The standard in the field was set with the following racemic resolution of secondary alcohols the transesterification of vinyl acetate to (S)-O-acetyl phenylethanol was catalyzed at room temperature by (isopropylamino)cyclopentadienylruthenium chloride and CALB with 97% yield and > 99% e.e. A reaction temperature of 25 °C, a reaction time of 30 h, and use of molecular sieve 4 A as a water trap, sodium carbonate as base, and vinyl acetate as acyl donor, are all major improvements over the previous state-of-the-art (Choi, 2002). 

More recently, cationic intermediates have been observed in the Heck reactions of arene diazonium salts catalyzed by triolefinic macrocycle Pd(0) complexes [17,59], o-iodophenols and enoates to form new lactones [60], and o-iodophenols with olefins (the oxa-Heck reaction) [61 ]. In the first case ions were formed by oxidation of the analyte at the capillary, or by association of [NH4] or Na". In the two other cases ionization occurred through the more typical loss of a halide ligand. The oxa-Heck reaction provides a good example of how these experiments are typically performed and the type of information that can be obtained. The oxyarylations of olefins were performed in acetone, catalyzed by palladium, and required the presence of sodium carbonate as base. Samples from the reaction mixtures were diluted with acetonitrile and analyzed by ESI(+)-MS. Loss of iodide after oxidative addition of o-iodophenol to palladium afforded positively-charged intermediates. Species consistent with oxidative addition, such as [Pd(PPh3)2(C6H50)], and the formation of palladacycles of the type seen in Scheme 8 were observed. Based on this, a mechanism for the reaction was proposed (Scheme 8). 

Sulfonamides. In the first step of a synthesis of 2-aminobenzophenone Scheifele and De Tar converted anthranilic acid into p-toluenesuffonylanthranilic acid using sodium carbonate as base if sodium hydroxide is used the main product is the tosic... 

In order to distinguish between a mechanism proceeding via a symmetrical cyclopropanone intermediate (Favorskii reaction) and a mechanism closely related to the benzilic acid rearrangement and called semibenzilic (or quasi-Favorskii) rearrangement, the ring contraction of 2-bromocyclobutanone was studied in deuterium oxide using sodium carbonate as base (50 C) or in boiling deuterium oxide only. 

The oxidation of the propargyl sulfide (469) with MCPBA and sodium carbonate as base was accompanied by a prototropic rearrangement to the corresponding allene sulfone (470) the same product was formed by oxidation of the parent allene sulfide (471). 

Several different transition metal-catalyzed reactions with the 2(li-f)pyrazinone template have been evaluated. The Suzuki-Miyaura coupling was efficient in introducing aryl groups to both the 3 and the 5-positions of the heterocycle. The 3-arylated product could be isolated in 75% yield by using 1.1 equivalents of boronic acid and sodium carbonate as base whereas use of 2.2 equivalents of boronic acid with cesium carbonate yielded the 3,5-disubstituted compound in 52% yield (Scheme 15.21) [56]. Efforts to widen the utility of this Suzuki-Miyaura reaction to include solid-phase reactions met with difficulties, because the reaction was problematic to drive to completion [57]. Other teams have also reported problems with Suzuki-Miyaura couplings on polymeric supports [44, 58]. 

Compared to that of the Ruzicka protocol, the Claisen-Geuther ester condensation in this synthesis was optimized from 17% to 64% by replacement of sodium ethoxide with sodium or sodium amide. In addition, the cyclization to form the piperidinyl ring is carried out in a two-phase solvent system (H2O and ether) using sodium carbonate as base. ... 

The Miyaura and Batey groups have also independently reported the use of rhodium catalysts for addition to aldehydes in the presence of phosphine ligands.Tautens has shown that [Rh(cod)Cl]2-catalysed reactions of heterocyclic alkynes with arylboronic acids in the presence of water-soluble ligands and sodium dodecyl sulfate (SDS) and sodium carbonate as bases affords trisubstituted alkenes in high regio-selectivity. ... 

Of greater versatility is an extension of Albert and Royer s acridine synthesis. The first successful use of this in the quinazoline series was for the removal of the chlorine atom in 2-chloro-4-phenylquin-azoline, although it had been used previously to prepare 8-nitro-6-methoxyquinazoline in very poor yield. The 4-chloroquinazoline is converted to its 4-(A -toluene-p-sulfonylhydrazino) quinazoline hydrochloride derivative which is decomposed with alkali in aqueous ethylene glycol at lOO C (Scheme 13). The yields are high (60-70%) when R is Me, Cl, OMe but low when R is NO2, and in the latter case it is preferable to use dilute sodium carbonate as the base. This reaction is unsatisfactory if the unsubstituted pyrimidine ring is unstable towards alkali, as in 1,3,8-triazanaphthalene where the pyrimi-... 

C-5 substituent either a pyrimidine (98) (when = NR2) or an isothiazole (99) (when R = Ar) are finally obtained. Sodium hydride as base resulted in ring fragmentation to give the open-chain adduct (100). Multistep mechanisms are proposed for these transformations (89BCJ1086>. The behavior of methylthio and dialkylamino salts (5 R = SMe and NRj, respectively) is quite similar and both give with carbon nucleophiles (e.g. Meldrum s acid) the same alkylidene derivative (97) (X , = Meldrum s acid residue) <(85CC696,88JCS(P1)899>. 

The use of soluble metal catalysts makes it possible to react 8 and its substituted derivatives with aryl bromides and triflates at 100 °C. The catalyst systems that have been used are Pd2(dba>3 and ( )BINAP with calcium carbonate as base (dba = dibenz[ ,. ]anthracene, BINAP = 2,2-bis(diphenyl-phosphanyl)-l,l-binaphthyl)<2000JA2178>, and 2-(di-r-butylphosphino)biphenyltris(dibenzylideneacetone)palladium with sodium yt-butoxide as base <2003T3109>. 

Organic Materials. The sol-gel chemistry of organic materials is similar to that of inorganic materials. The first organic aerogel was prepared by the aqueous polyconclensation of resorcinol with formaldehyde using sodium carbonate as a base catalyst. 

The homogeneous catalytic olefinic substitution, like the carboalkoxylation, does not generally proceed in high yield with aromatic chlorides under the usual conditions. A heterogeneous catalyst, palladium on charcoal, has been reported to cause chlorobenzene and other aromatic chlorides to react with styrene and styrene derivatives, with sodium carbonate as a base at 100° 30, 3]). In our laboratory, we have found the reactions occur as described, but the catalyst is apparently rapidly deactivated. 

Cyclizations occur with secondary amine derivatives, also. N-Allyl-o-iodoaniline produces 3-methyl-indole, for example, in high yield at 25 C using sodium carbonate as the base with tetrabutylammonium chloride in DMF solution (equation 24).7S Similar procedures have been applied to the synthesis of in-... 

Treatment of the sodium salt of 2-cyanocyclododecanone (VII/109) with a>-haloisocyanates yields the 14-membered imide VII/U2. Two cyclization products of VII/112 were obtained in the presence of potassium carbonate as base. In the C-alkylated bicycle, VII/113, the central bridge bond is solvolyzed to form the 16-membered amide VII/114. The O-alkylated bicycle, VII/US, which is the minor product, was not investigated further. When 2-chloroethyl isocyanate was used as reagent, the analogue of VII/115 was formed directly. Because of its multistepcharacter the reaction resembles MIMIRC (Scheme VII/9) [59] [60]. 

These two diastereoisomeric cyclohexyl chlorides derived from menthol react very differently under the same conditions with sodium ethoxide as base. Both eliminate HC1 but diastereoisomer A reacts rapidly to give a mixture of products, while diastereoisomer B (which differs only in the configuration of the carbon atom bearing chlorine) gives a single alkene product but very much more slowly. We can safely exclude El as a mechanism because the same cation would be formed from both diastereoisomers, and this would mean the ratio of products (though not necssarily the rate) would be the same for both. 

Bromination of 1-alkynes with N-bromosuccinimide in the presence of catalytic amounts of silver nitrate, was used first for the bromination of 17-ethynyl steroids.7 Similarly, N-iodosuccinimide led to 17-iodoethynyl steroids, lodination of propiolates in this way has not been studied. A recent method of preparation of 1-iodoalk-l-ynes under phase-transfer conditions involves molecular iodine and copper(l) iodide as catalyst, in the presence of potassium or sodium carbonate as a base. Ethyl 3-iodopropiolate was prepared by this route in 80% yield.8... 

Michael addition to a, -unsaturated aldehydes The Michael addition of malonic ester and acetoacetic ester to a,0-unsaturated aldehydes can be carried out in moderate yields under phase-transfer conditions with sodium or potassium carbonate as base and benzyltriethylammonium chloride as catalyst (equation I). 

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