Yield from reactions

Under optimum conditions electron transfer can produce excited states efficiently. Triplet fluoranthrene was reported to be formed in nearly quantitative yield from reaction of fluoranthrene radical anion with the 10-phenylphenothia2ine radical cation (171), and an 80% triplet yield was indicated for electrochemiluminescence of fluoranthrene by measuring triplet sensiti2ed isomeri2ation of trans- to i j -stilbene (172). 

Alkali metal xanthates are prepared in high yield from reaction of amyl alcohols with alkah metal hydroxide and carbon disulfide (39—42). The xanthates are useful as collectors in the flotation of minerals and have minor uses in vulcani2ation of mbber and as herbicides (39,41). 

Esters of / fZ-amyl alcohol can be obtained by acylation of 2-methyl-2-butene in the presence of trifluoromethanesulfonic acid (44). The esters produced, in high yields, from reaction of amyl alcohols with carboxyHc anhydrides, are used as intermediates for preparation of pyryflum salts (45,46) and alkaloids (47). Tria2oles prepared by acylation of 3-methyl-1-butanol are useful as herbicides (48). 

If the more activated alkene 2-vinylpyridine is used in place of styrene with the same catalysts and the same range of substrates, anti-Markovnikoff hydroamination is also found. Thus, N-[2-(2 -pyridyl)ethyl]piperidine was isolated in 53% yield from reaction of 2-vinylpyridine with piperidine in the presence of [Rh(COD)2]+/2PPh3 under reflux. N H addition was observed with other amines, the remaining product in all cases being primarily that from oxidative amination (Table 12). When the catalytic reaction was run in the absence of phosphine, the yield of hydroamination product increased dramatically.171... 

The intermediate acylamidine 244 functions as the three-atom component in reaction with hydroxylamine to give the [l,2,4-oxadiazol-5-yl]pyrazole 245, where the intermediate acylamidine 244 was obtained in good yield from reaction of the corresponding amide 243 with dimethylacetamide-dimethyl acetal (Scheme 37) <1999JME2218>. 

Fewer routes are known for the preparation of dithiophosphonic acids. Nevertheless sodium dithiophosphophonates have been prepared in high yields from reaction of dithiadiphosphetane disulfides with a sodium alkoxide or aryloxide in the corresponding alcohol solution (Equation 25).40,41... 

The reaction of 2-anilino-l,4-naphthoquinone 374 with benzoylacetic acid hydrazide gives 3-hydrazino-pyrazolyl derivative 375, that is acetylated to produce 5-[[l,4-dihydro-l,4-dioxo-3-(phenylamino)-2-naphthalenyl]sulfonyl]-3-methyl-6-phenyl-5/7-pyrazolo[5,l-c][l,2,4]triazole 51. This latter derivative is also obtained in 51% yield from reaction of 374 with benzoylacetic acid hydrazide in the presence of a mixture of acetic acid-sodium acetate <2004PS(179)1907> (Scheme 39). 

The reaction of the -C(Hal)=N-function with azide ion or hydrazoic acid is known to give the tetrazole system. As part of a mechanistic study of the one-pot synthesis of an azadibenzoporphyrine in 84% isolated yield from reaction of a 1-bromobenzopyrromethene hydrobromide 74 with sodium azide at 140 °C, 74 was treated with azide at lower temperature (60 °C) in an attempt to isolate the proposed azide mechanistic intermediate 75 however, the fused tetrazole 76 was isolated in 47% yield (identified by X-ray analysis) (Equation 4) <1999MI530>. Upon heating a dimethyl formamide (DMF) solution of tetrazole 76 to 140°C for 1 h, the desired porphyrin was indeed obtained in 14% yield, consistent with the temperature-dependent equilibrium between tetrazole and azide that has been observed with some fused tetrazoles. 

Finally, a particular surprise from this work has been (cp-K+)2(KSng ), the structure of which appears to represent a partial transition to an Intermetallic-llke bonding. The compound which was isolated in respectable yield from reactions of K-Hg-Sn alloys with crypt in en exhibits infinite chains K(4)-Snq-K(5)-Sng-K(4) running diagonally through the tricllnlc cell, K(4) and K(5) being located on centers of symmetry at 0,0,0 and /2 V2 2 crypt-lC " cations fill the remainder of the... 

Oxidation with bis(p-methoxyphenyl) telluroxide (general procedure All the reactions are performed at room temperature under Nj in CHCI3 or CHjClj. Approximately 10 mL of solvent is used for every 100 mg of substrate. For thiocarbonyl derivatives, 1.1 equiv of the reagent is used, for thiols 0.55 equiv. The mixtures are concentrated by evaporation and submitted to thin layer or column chromatography to isolate the products. An2Te is always recovered in a yield of 64-96%, while sulphur or selenium is always recovered in near quantitative yields from reaction with thio- or selenocarbonyl derivatives. 

Reactions between aromatic hydrocarbon radicabcations and cyanide ions, with few exceptions, give low yields of nuclear substitution products [76], In some cases, better results have been obtained by anodic oxidation of the aromatic compound in an emulsion of aqueous sodium cyanide and dichloromethane with tetra-butylammonium hydrogen sulphate as a phase transfer agent [77, 78]. Methoxy-benzenes give exceptionally good yields from reactions in acetonitrile containing tetraethylammonium cyanide, sometimes with displacement of methoxide [79, 80]... 

A recent report on trifluoromethylsulfenylation of (3-keto acids and derivatives describes isolation of 29 in good yield from reaction of 27 with trifluoromethyl-sulfenyl chloride (Scheme 6.10). Mechanistically, this was rationalized via electrophilic attack of trifluoromethylsulfenyl chloride on the enamine tautomer 27a to generate 28 followed by intramolecular cyclization through the imide oxygen with concomitant loss of CF3SH to produce 29. The product was characterized spectroscopically. 

Nitrosamine yields %) from reactions according to equations (4), (7), and (8) are at specific analysis times. The reported yields are not the maximum yields. The estimated half-life is for the parent nitrosamine (left column) and assumes conversion to VII only. Reactions were conducted in tetrahydrofuran at 70°C. Substrate, 0.42 M potassium t-butoxide, 0.56 M t -butyl alcohol,... 

The tricyclic system 315 is formed in moderate yields from reaction of 313 with 314. The reactions of 313 with 316 and 318 give 317 and 319, respectively (Scheme 24) <2002JST41>. 

Reaction of 103 with guanidine affords 4,6-diaminopyrazolo[3,4-d]-pyrimidine 111 as a main product (75JHC1199 79AP610 79AP873 79M11). Formation of 112 in 3-5% yields from reaction of 103 (R =... 

Atkyllithium reagents. This aromatic radical anion (1) is particularly effective for conversion of alkyl halides into alkyllithium reagents. These products are formed in 93-95% yield from reactions conducted in THF at — 78°. 

The cyclazine (Iv) was the only product isolated in poor yield from reaction of pyridine and methyl propiolate in acetonitrile. The indolizine derivative (35) may be an intermediate, since it was obtained from a similar reaction in ether.39 2-Acetylpyridine and ethyl pyridine-2-carboxylate reacted similarly.40... 

The synthesis of aromatic tellurides has been performed via the reaction of iodoarenes (0-, m- and p-iodonitrobenzene, and di- and tri-methyliodonitrobenzenes) with phenyltelluride in HMPA at 80-90 C, preferably in the presence of Cul. Yields range between 53 and 95%.218 Symmetrical diaryl tellurides (69 R = 3-Me, 4-Me, 2,4-Me2,2,4,6-Me3,4-MeO) were prepared in good yields from reaction of nonac-tivated aryl iodides with Na2Te in DMF at 60 "C.219 The mechanisms of these reactions, which are limited to the iodoarenes, have not been discussed. 

CNXylyl) formed in high yield from reactions with CNXylyl in acetone (18). 

R2C—0 - R2CF2. This reaction has been carried out directly with diethyl-aminosulfur trifluoride (DAST, 6, 183-184). It can also be effected by reaction of hydrazones of aldehydes or ketones with bromine fluoride, BrF, generated in situ from NBS and Py(HF)n. Yields from reactions of hydrazones of ketone are in the range 30-95% the yield from reaction of the hydrazone of an aldehyde was 28%. 

Benzylic hydroxylation.3 Direct introduction of the Cl0-hydroxyI group into anthracycline glycosides can be effected with (CH3)3NO. Thus 1 is converted into oxaunomycin (2) in 82% yield from reactions in DMF. The yield is only 53% when acetone is the solvent, and is also lower (34%) in the absence of the Cn-hydroxyl group. 

The anion [Ce4(0H)2(H20)9(P2Wi6059)2]14 (Figure 24) is isolated in good yield from reaction of Ce(NC>3)3 with Ki2H2P2Wi2048-nH20/ a hexavacant derivative of the Wells-Dawson anion U WisCfe]6-, and Na2W04. The anion has... 

Iron complexes can also catalyze allylic amination [31,32]. Enders et al. have demonstrated the nucleophilic addition of various acyclic and cyclic amines to the optically active l-methoxycarbonyl-3-methyl-(T)3-allyl)-tetracarbonyliron cation 49 formed in high yield from reaction of 48 with iron carbonyls. Oxidative removal of the tetracarbonyliron group by reaction with CAN gives 50 with high optical purity and retention of the stereochemistry (Eq. (12)) [31]. The reaction proceeds well for the different amines, and has been used for the synthesis of a compound showing cytotoxic activity against diverse cell lines [31b]. 

Bis pentafluoroethyl ditellurium was isolated in low yields from reaction mixtures obtained by heating tetratellurium bis[hcxafluoroarsenate] to 100° under 15 atmospheres of tetrafluoroethene1 2. 

Diorgano tellurium dithiocarbamate halides are isolated in quantitative yield from reaction mixtures containing equimolar amounts of a diorgano tellurium dihalide and an ammonium or sodium dithiocarbamate1,2. 

Heterosubstituted 1,3-dienes. Some alkenylmetals substituted by OR, SR, or SiR, can be coupled with alkenyl halides (or aryl halides) in the presence of this Pd(0) catalyst. Alkenylzinc reagents, prepared by reaction of alkenyllithiums with ZnCh, and alkenyl-alanes are the most useful. Yields from reactions with organoboronates are low. 

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