Aldehydes trifluoromethanesulfonate

The Frasca method for obtaining 1-arylindazoles also involves a C(3)—C(3a) ring closure (67CJC697). It consists in the cyclization of p-nitrophenylhydrazones of ketones and aldehydes with polyphosphoric acid. The Barone computer-assisted synthetic design program has found several new methods for preparing indazoles (79MI40409). The selected method involves the transformation of jV, jV -diphenylhydrazides (596) into 1-phenylindazoles (597) by means of trifluoromethanesulfonic anhydride. The yields vary from 2% (R = H) to 50% (R = Ph). 

A novel and versatile method for preparing polymer-supported reactive dienes was recently developed by Smith [26]. PS-DES (polystyrene diethyl-silane) resin 28 treated with trifluoromethanesulfonic acid was converted to a polymer-supported silyl triflate 29 and then functionalized with enolizable a,jS-unsaturated aldehydes and ketones to form silyloxydienes 30 and 31 (Scheme 4.4). These reactive dienes were then trapped with dienophiles and the Diels Alder adducts were electrophilically cleaved with a solution of TFA. 

The reaction of crotonaldehyde and methyl vinyl ketone with thiophenol in the presence of anhydrous hydrogen chloride effects conjugate addition of thiophenol as well as acetal formation. The resulting j3-phenylthio thioacetals are converted to 1-phenylthio-and 2-phenylthio-1,3-butadiene, respectively, upon reaction with 2 equivalents of copper(I) trifluoromethanesulfonate (Table I). The copper(I)-induced heterolysis of carbon-sulfur bonds has also been used to effect pinacol-type rearrangements of bis(phenyl-thio)methyl carbinols. Thus the addition of bis(phenyl-thio)methyllithium to ketones and aldehydes followed by copper(I)-induced rearrangement results in a one-carbon ring expansion or chain-insertion transformation which gives a-phenylthio ketones. Monothioketals of 1,4-diketones are cyclized to 2,5-disubstituted furans by the action of copper(I) trifluoromethanesulfonate. ... 

CHROMIUM TRIOXIDE-PYRIDINE COMPLEX, preparation in situ, 55, 84 Chrysene, 58,15, 16 fzans-Cinnamaldehyde, 57, 85 Cinnamaldehyde dimethylacetal, 57, 84 Cinnamyl alcohol, 56,105 58, 9 2-Cinnamylthio-2-thiazoline, 56, 82 Citric acid, 58,43 Citronellal, 58, 107, 112 Cleavage of methyl ethers with iodotri-methylsilane, 59, 35 Cobalt(II) acetylacetonate, 57, 13 Conjugate addition of aryl aldehydes, 59, 53 Copper (I) bromide, 58, 52, 54, 56 59,123 COPPER CATALYZED ARYLATION OF /3-DlCARBONYL COMPOUNDS, 58, 52 Copper (I) chloride, 57, 34 Copper (II) chloride, 56, 10 Copper(I) iodide, 55, 105, 123, 124 Copper(I) oxide, 59, 206 Copper(ll) oxide, 56, 10 Copper salts of carboxylic acids, 59, 127 Copper(l) thiophenoxide, 55, 123 59, 210 Copper(l) trifluoromethanesulfonate, 59, 202... 

Additions of the Reformatsky-type reagents to aldehydes can also proceed in ionic solvents (Scheme 108).287 Three ionic liquids have been tested 8-ethyl-l,8-diazbicyclo[5,4,0]-7-undecenium trifluoromethanesulfonate ([EtDBU][OTf]), [bmim][BF4], and [bmim][PF6]. The reactions in the first solvent provided higher yields of alcohols 194 (up to 93%), although results obtained for two other ionic liquids were also comparable with those reported for conventional solvents. 

A diastereoselective synthesis of /3-(iV-acylamino)aldehydes was accomplished via ruthenium-catalyzed isomerization of 0-vinyl-iV,0-acetals followed by rearrangement in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) (Scheme 36).63... 

Aldehyde 26 was treated with hydroxylamine hydrochloride in refluxing methanol to give a mixture of (E)- and (Z)-pyrrolotriazine 40 in 59% and 21% yield, respectively. Dehydration of aldoxime 40 with trifluoromethanesulfonic anhydride and triethylamine in dichloromethane afforded triazine 41. Conversion of the nitrile 41 to the deprotected amide 42 was accomplished in 96% yield on treatment of 41 with basic hydrogen peroxide in ethanol <2001CAR77>. 

Alternatively, the authors have evaluated the polymer-bound scandium(III) bis (trifluoromethanesulfonate) as catalyst, and it proved to be slightly more active than the previous one. In a series of runs, the authors have re-evaluated the method and produced a library of 50 a-aminonitriles starting fi om ahphatic and aromatic aldehydes. In all runs, the reported yields were >99.6%. 

These reagents are also useful for the preparation of 1,2-diols. Upon exposure to Lewis acids such as boron trifluoride etherate (BFa-OEta), the a-alkoxy and oc-siloxyallyl stannanes undergo a stereospecific, intermolecular 1,3-isomerization to give y-alkoxy- and y-siloxy allylic stannanes.3. .7 When tert-butyldimethylsilyl trifluoromethanesulfonate is substituted for chloromethyl methyl ether in the above procedure, the isomeric -y-siloxy allylic stannane can be obtained directly with no loss of enantioselectivity.6 These stannanes can then be added to various aldehydes to give monoprotected 1,2-diols with high diastereoselectivity.8... 

The condensation of the diamide 371 with the corresponding aldehydes 372 and 373 afforded 374 and 375, respectively, which upon treatment with anhydrous trifluoromethanesulfonic acid in MeCN gave the cyclized products 376 and 377, as a single diastereoisomer (Scheme 79). The action of m-chloropcroxybenzoic acid, followed by the treatment of the monosulfoxide with perchloric acid, resulted in the 1,2,5-dithiazepines 378 and 379 <2000AGE3866>. 

Oxidation. This reagent is prepared by reaction of CAN with K2C03 (2 equiv.) to form Ce(C03)2, which is then treated with trifluoromethanesulfonic acid (4 equiv.). This oxidant is effective for oxidation of benzylic alcohols to aldehydes (72-92% yield), and of alkylarenes to aldehydes or ketones (65-70% yield). 

Treatment of 2-(trimethylsilyl)phenyl trifluoromethanesulfonate 171 with KF generates benzyne, which can then react with aromatic aldehydes to furnish 9-aryl-97/-xanthenes in moderate yield (Scheme 55). Electron-rich aromatic aldehydes are necessary to obtain high yields of the desired xanthenes <20040L4049>. 

A new synthetic approach to polycyclic aromatic compounds has been developed based on double Suzuki coupling of polycyclic aromatic hydrocarbon bis(boronic acid) derivatives with o-bromoaryl aldehydes to furnish aryl dialdehydes. These are then converted to larger polycyclic aromatic ring systems by either (a) conversion to diolefins by Wittig reaction followed by photocyclization, or (b) reductive cyclization with trifluoromethanesulfonic acid and 1,3-propanediol (Eq. (12)) [30]. 

Reaction of benzaldehyde and its 4-nitro derivative with the enantiopure diene 796 in DCM and in presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) afforded the condensed enantiopure oxathiocanes 777 and 778 (50% yield). The reaction path began with the ionic addition of the diene 796 onto the carbon atom of the aldehyde function in 797a,b activated by trimethylsilyl cation attack to the carbonyl oxygen. 

Recently, the [ F](luorobcnzalciehyde 5 was obtained by nucleophilic substitution of the 2-formyl-A, A, A -trimethylbenzeneammonium trifluoromethanesulfonate precursor 4 using no-carrier-added [K/222] F as the [ F]fluoride source. The ammonium trifluoromethanesulfo-natc4 is obtained by quaternization of the dimethylamino compound 3. The [ F]fluorobcnz-aldehyde 5 is used in the preparation of interesting radiopharmaceutical a-metliyl-L-amino acids for positron emission tomography, as well as potential inhibitors of enzymatic functions. 

Because tin(ll) enolates of thioesters are generated upon reaction of tin(ll) thiolates with ketenes, the optically active p-hydroxy thioesters are also easily synthesized by way of the aldol reaction with aldehydes in the presence of tin(Il) trifluoromethanesulfonate and chiral diamine 1 (eq 7)7... 

Asymmetric Allylation of Prochiral Aldehydes. The asymmetric allylation reaction is useful for stereoselective carbon-carbon bond formation, and therefore development of an effective method for the synthesis of optically active homoallyl alcohols was sought. A chiral allylating agent, readily generated from tin(II) trifluoromethanesulfonate, chiral diamine 1, and allyldi-isobutylaluminum, was efficiently employed in the asymmetric allylation of aldehydes in 1996 (eq 16). ... 

The asymmetric aldol reaction of enol silyl ethers of thioesters with aldehydes is performed in high enantiomeric excess by employing a chiral promoter, tin(II) trifluoromethanesulfonate coordinated with chiral diamine 1 and tri-n-butyltin fluoride (eqs 20 and 21). Highly enantioselective aldol reactions of achiral ketene silyl acetals with achiral aldehydes are carried out by means of the same chiral promoter (eq 22). ... 

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