Benzenethiol esters

Oxetanones can be generally prepared by displacement processes on various /3-substituted carboxylic acids or by halolactonization of /3,y-unsaturated acids. A very general and reliable method consists of treatment of a /8-hydroxy acid with benzenesulfonyl chloride and pyridine at 0°C (equation 91). The yields of /3-lactones are usually in excess of 80% (79JOC356, 74JOC1322). An alternative method involves cyclization of the benzenethiol ester of a /3-hydroxy carboxylic acid by means of mercury(II) methanesulfonate in acetonitrile (equation 92). The yields were excellent in the two cases reported (76JA7874). 

By Reduction of Carbonyl Compounds. Use of high (10 kbar) pressures has been shown to effect trialkylstannane reductions of ketones in the absence of radical initiators or Lewis acids.10 Zinc borohydride has been demonstrated to be a mild reducing agent for the conversion of benzenethiol esters into alcohols in good yield. Use of mixed solvents containing methanol has been found to confer some chemoselectivity upon reductions with lithium borohydride and permits enhanced rates of reduction of esters, lactones, and... 

From this study of possible variations, Masamune was able to achieve the first partial synthesis of the macrolides cytochalasin A and B, 2 and 3, by use of silver(I) trifluoroacetate for activation of a benzenethiolate ester, RCOSCeH. . 

Trimethylsilyl enol ethers of acyltrimethylsilanes. These useful silanes (3) can be prepared from benzenethiol esters (1) by conversion into the silyl enol ethers... 

Ring-opening reactions with 3-alkylaziridine esters 36 take a similar course. The reactions are in practically all cases regio- and stereospecific with attack at C-3. An important difference is that the aziridine ring needs to be activated by an electron-withdrawing substituent, such as a tosyl or a benzyloxycarbonyl group. In addition, for benzenethiol, indole, and DMF, catalysis with BF3 was necessary (Scheme 22) [31]. 

Because anti/syn ratios in the product can be correlated to the E(0)/Z(0) ratio of the involved boron enolate mixture,10b initial experiments were aimed at the preparation of highly E(0)-enriched boron enolate. The E(0)/Z(0) ratio increases with the bulk of the alkanethiol moiety, whereas the formation of Z(O) enolates prevails with (S )-aryl thioates. (E/Z = 7 93 for benzenethiol and 5 95 for 2-naphthalene thiol esters). E(O) reagent can be formed almost exclusively by reaction of (5)-3,3-diethyl-3-pentyl propanethioate 64 with the chiral boron triflate. High reactivity toward aldehydes can be retained in spite of the apparent steric demand (Scheme 3-22).43... 

The photochemical reduction of Barton ester 40 is depicted in Scheme 12. A series of hydrogen atom donors were screened. A stoichiometric amount of benzenethiol at - 78 °C provided the product in 86% ee (entry 3). This implies that, in the presence of an efficient hydrogen atom donor, radical trapping is competitive with the ring/radical inversion, generating an enantiomeri-... 

The method outlined here competes well with the method developed earlier by Danheiser, et al.618 Its superiority is based on the fact that phenyl ester enolates give almost the same results as the S-phenyl thiolester enolates. However, handling the malodorous benzenethiol for the preparation of the active acid derivative and during workup of the p-lactone can be avoided. In addition, phenol is much cheaper than benzenethiol. The method is well suited for the preparation of p-lactones from symmetrical and unsymmetrical ketones. In addition to 3,3-dimethyM-oxaspiro[3.5]nonan-2-one, ( )-3-ethyl-1-oxaspiro[3.5]nonan-2-one and (3R, 4R )- and (3R, 4S )-4-isopropyl-4-methyl-3-octyl-2-oxetanone were prepared by this procedure in high yields (Notes 11 and 12). In the case of unsymmetrical ketones the less sterically crowded diasteroisomer is formed preferentially. With aldehydes as the carbonyl component the yields are unsatisfactory, because of the competitive formation of 1,3-dioxan-4-ones.6... 

Nucleophilic Substitution Reactions. Many of the transformations realized through Michael additions to quinones can also be achieved using nucleophilic substitution chemistry. In some instances die stereoselectivity can be markedly improved in this fashion, e.g., in the reaction of benzenethiol with esters (R = CH3C=0> and ethers (RJ = CH,) of 1,4-naphthoquinones. 2-Bromo-5-acetyloxy-1,4-naphthoquinone, R1 — Hr, yields 75% of 2-thiophenyl-5-acetyloxy-1,4-naphdloquinone. R1 = SCr.Hv 3-Bronio-5-methoxy-l,4-naplitlioquinone, R2 = Br, yields 82% of 3-thiophenyl-5-methoxy-1,4-naphthoquinone R2 = SCr.IIs. 

Benzenethiol (9) itself can partake in 1,4-addition to the methyl ester 10 of 2-fluoro-3-methoxy-acrylic acid to yield the nionothioacetal ll. ... 

Therefore, the cis-tmns isomerization mechanism in PUFA was revisited.The reactions were initiated by continuous °Co y-irradiation of NjO-saturated terf-butanol solutions containing j8-mercaptoethanol or benzenethiol and PUFA esters. Product studies led to a proposed detailed mechanistic scheme (Scheme 2). 

A series of novel 2-amino-6-aryl-9-[2(phosphonomethoxy)ethyl] purine bis (2,2,2-trifluoroethyl) esters (404) has been synthesized by satisfactory regioselec-tive alkylation of 2-amino-6-chloropurine (405) with the bis(tri-fluoroethyl)(2-iodoethoxy)methylphosphonate(406), followed by exchanging the chlorine atom in the resultant intermediate (407) for various substituted and unsubstituted benzenethiols and naphthalenethiols. 6-Phenylthio- and 6-(methoxyphenyl)thio-derivatives showed potent Hepatits B-specific antiviral activity in vitro, and 9[2-(phosphonomethoxy)ethyl] adenine and 9[2-(phosphonomethoxy)ethyl] 2,6-diaminopurine have a broad spectrum of activity against viruses (Scheme 105). ... 

Metal thiolates or benzenethiols in the presence of triethylamine also react very smoothly with di-ketene to yield S-alkyl (35) or S-aryl acetothioacetates (36). The p-keto thioesters (35) can be used in exceptionally mild preparations of P-keto amides (37), whereas (36) can be cyclized by Lewis acids to form thiocumarins (38). The S-f-butyl thiol ester (35) is also a suitable substrate for C-alkylation in the P-position or, after double deprotonation, in the 8-position (Scheme 3). ... 

Methane- and ethanethiol underwent addition to methylenecyclopropane to give the respective (alkylsulfanylmethyl)cyclopropane 1 a, b in 63 and 44% yield. Benzenethiol reacted with the methyl ester of Feist s acid in the same manner to give 1 c, but required the addition of di-/er/-butyl peroxide. ... 

Formation of sulfide with concurrent ester hydrolysis was achieved when various Cj cyclopropyl cephalosporin 5-oxide 2,2,2-trichloroethyl esters were treated with phosphorus trichloride followed by zinc under acidic conditions. Sulfoxide reduction also occurred on treatment of cyclopropyl phenyl sulfoxide with a mixture of benzenethiol and chlorotrimethylsilane in chloroform to give cyclopropyl phenyl sulfide in 76% yield and on reaction of various substituted cyclopropyl phenyl sulfoxides with diisobutylaluminum hydride. ... 

Benzaldehyde, 100, 105, 154, 175, 336 Benzamide, 320 Benzene, 134, 154, 198, 286 Benzenesulfenyl chloride, 182 Benzenesulfinic acid sodium salt, 18 Benzenesulfonamide, 18 Benzenesulfonyl azide, 17—18 Benzenesulfonyl bromide, 18 Benzenesulfonyl chloride, 17 N-Benzenesulfonylformimidic acid ethyl ester, 18-19 Benzenethiol, 182 Benzhydrol, 238 Benzil, 312 Benzimidazole, 126 2,1-Benzisothiazole, 290 Benzobicyclo[2.2.2]octadiene, 46 Benzocyclobutadiene, 227 Benzohydroquinones, 60 Benzoic acid, 175... 

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