Phenyl sulphones, synthesis

A second paper161 describes the use of the same base in either THF or t-butanol for the elimination of a-acetoxy phenyl sulphones as outlined in equation (68), in essence a reaction sequence very similar to the Julia olefin synthesis (Section III.B.3) except in the method by which the sulphonyl group is finally removed. 

Three reaction sequences, all of a similar nature, have been published by Fujita and coworkers. The first175 is an alkene synthesis in which only three examples that involve sulphones are given. The most useful of these is a conversion of nerly phenyl sulphone (from neryl chloride) into aCn triene (75%), with the extra carbon atom being supplied by the iodomethylstannane reagent. The reaction proceeds spontaneously, with apparent retention of configuration at the Z alkene, as in equation (72). 

This synthetic sequence for an olefin synthesis has been further developed by Kocienski who has shown that eliminative desulphonylations carried out on / -acyloxysulphones are remarkably stereoselective for the synthesis of trans-disubstituted-olefins. The method has wide applicability in that a-lithio phenyl sulphones are readily generated, and are readily coupled to aldehydes or ketones, to give j8-hydroxysulphones. The hydroxyl function of these is then esterified and the synthesis is completed by the reductive elimination with sodium amalgam. Kocienski has prepared two reviews that summarize his syntheses of a range of natural products - one of which is diumycinoP obtained... 

Using a soliddiquid two-phase system of the sodium arenesulphinite in 1,2-dimethoxyethane, or in the complete absence of a solvent, permits the use of less reactive haloalkanes [3,4], This is a particularly good method for the preparation of sulphones where the sulphinic acid salts are readily available and, in addition to the synthesis of the tolyl sulphones listed in Table 4.28, it has been used to prepare phenyl sulphones [3]. Phenyl sulphones have also been prepared in good yield using a polymer supported catalyst [5] (Table 4.29). As the system is not poisoned by iodide ions, reactive iodoalkanes can be used and there is the additional advantages in the ease of isolation of the product and the re-use of the catalyst. 

The potent biological activity (insect antifeedant, antitumour, antifungal) of warburganal (35) has stimulated considerable synthetic interest in this compound. Three total syntheses of this compound have been recorded in the period under review. " The synthesis by Tanis and Nakanishi has additional flexibility since the key intermediate diol (34) can be used in the syntheses of cinnamolide (36), drimenin (37), and polygodial (38). Both norisoambreinolide (39 R = O) and isoambrox (39 R = H2) have been synthesized from (40), the product of the stannic chloride-catalysed cyclization of farnesyl phenyl sulphone. Yahazunol (41), a bicyclofarnesyl hydroquinone, has been identified in the brown seaweed... 

In a synthesis of /3-damascenone (31), prenyl phenyl sulphone (141) reacted with the bromo-ester (142) to give methyl 5-phenylsulphonylgeranoate (143). Cyclization of (143) produced a mixture of the a- and /3-ring compounds (144) and (145). The former readily underwent an elimination to produce methyl safranate (146) which, with allyl-lithium, afforded /3-damascenone. Another... 

A further example of the use of phenyl sulphones in prenylation reactions is provided in the recent synthesis of deoxytrisporone (37) (Scheme 5)7 An interesting feature of this synthesis is the regiospecific acylation of the diol (35) with isobutyric anhydride. 

Electrochemical oxidations have been previously mentioned.122 A novel application is the regioselective epoxidation (80% conversion 90% selectivity) at the 6,7-bond of geranyl and neryl esters and phenyl sulphones.214 Another is the one-step conversion of olefins into allylic alcohols via electrooxidative-oxyselenylation-deselenylation, e.g. (97)—>(99). This method has been applied to the synthesis of (100) which can be converted (70%) into marmelolactone [(101) from quince], and... 

Homolysis of the S-acyl bond is responsible for formation of phenylthio-cyclohexane and 3-phenylthiocyclohexene from. SiS -diphenyl dithiocarbonate by irradiation in cyclohexene.117 A cyclic mechanism, however, has been proposed to account for the photodecomposition of certain carbohydrate dithiobisthio-formates.118 On irradiation, 0-ethyl thioacetate is converted into cis- and / 5-2,3-diethoxybut-2-ene, together with small amounts of 2,3-diethoxybut-l-ene, 2,3-diethoxybuta-1,3-diene, and 1-ethoxyethane-l-thiol.119 121 Free sulphur was trapped by reaction with 1,2-dimethyIenecyclohexane. Details of the photoelimination of sulphur dioxide from D-glucofuranosyl phenyl sulphone acetates have been published.180 An efficient synthesis of another 1,8-bridged naphthalene... 

The treatment of a dialdose derivative with lithiated methyl phenyl sulphone is discussed in chapter 11, and the preparation of a synthon of deazatunicamycin is covered in chapter 19. An improved synthesis of (6- C) aldohexoses from 1,2-Q-isopropvlidene-q-D-xylo-pentodialdo-l.4-furanose is included in chapter 2. The racemic synthesis of an aminosugar dialdose is mentioned in chapter 9. 

Ito and Kato and their respective co-workers have extended their closely related investigations of the synthesis of 10- and 14-membered cyclic terpenoids by intramolecular cyclizations of phenyl sulphides [e.g. (214) - (215)] and phenyl sulphones [e.g, (216) - (217)]. ""... 

Chapter IV. a-Chloromethylnaphthalene (IV,23) benzylamine (Gabriel synthesis) (IV,39) i r.N -dialkylanilines (from amines and trialkyl orthophosphates) (IV,42) a-naphthaldehyde (Sommelet reaction) (IV,120) a-phenyl-cinnamic acid (Perkin reaction using triethylamine) (IV,124) p-nitrostyrene (IV,129) p-bromonaphthalene and p naphthoic acid (from 2 naphthylamine-1 -sulphonic acid) (IV,62 and IV,164) diphenic acid (from phenanthrene) (IV,165). 

Fig. 3.12. Synthesis of the compounds by the methods (a) and (b). A = -NHC6H4S03H (dye la) A = -NHCH2CH=CH (dye lb) A = -OCH2CH=CH2 (dye lc). SP = N-(4 -sulpho)phenyl-3-methy 1-5-pyrazolone m-PDA = l,3-phenylendiamine-4-sulphonic acid. Reprinted with permission from T. Konstantinova et al. [90],...

Aryl glycosides of 2-amino-2-deoxy sugars, as might be expected, can be prepared by similar techniques as was illustrated by the synthesis of phenyl 3,4,6-tri-0-acetyl-2-acetamido-2-deoxy-p-D-glucoside and -D-galactoside by toluene -sulphonic acid catalysed reactions between phenol and the hexosamine penta-acetates These products were then anomerised using zinc chloride as catalyst to provide means of obtaining -anomers. 

Rearranged products of type R2YC = CR1R2 are obtained from the vinyl triazene 112 when R2 is an aiyl group and Rx is hydrogen or methyl and also when R2 is tolyl and Rx is phenyl. The acid-catalysed decomposition of vinyl triazene which occurs in very mild conditions has been exploited as a useful method for the synthesis of vinyl sulphonates (Jones and Maness, 1969, 1970 Modena and Tonellato 1971). 

The reaction of enamines and imines with acrylamide results in aza-annulation120,121. Other electrophilic alkenes which have been used to alkylate enamines and the products used in hetero- or carbocyclic synthesis include ethyl / -nitroacrylate122, where reaction occurs beta to the nitro not the ester group, 2-(phenylseleno)prop-2-enenitrile [CH2 = C(SePh)CN]123,124, phenyl a-phenylselenovinyl sulphone [CH2 = C(SePh)-S02Ph]124 and phenyl a-bromovinyl sulphone124. An electrophilic allene, phenylsulpho-nylpropadiene, has also been used to alkylate enamines125 (Scheme 44). 

The alkylation of acyclic imines with electrophilic alkenes such as acrylonitrile, methyl acrylate or phenyl vinyl sulphone is also sensitive to steric effects and again, as a consequence, only mono-alkylation occurs398. The regioselectivity of the reaction in methanol varied from 100% attack at the more substituted a-position to 70% attack at the less substituted a -position depending upon the steric inhibition manifested and the stabilization of the competing secondary enamine tautomers (vide infra) (Scheme 204). In contrast, the reaction of butanone and other methyl ketone imines with phenyl vinyl ketone occurs twice at the more substituted a-position but this is then followed by a double cyclization process (Scheme 205). Four carbon-carbon bonds are formed sequentially in this one-pot synthesis of the bicyclo[2.2.2]octanone 205 from acyclic precursors399,400. 

The third synthesis, by Crombie et al., utilizes the base-catalysed condensation of the trans,trans-phenyl farnesyl sulphone (10) with trans,trans-Qthy farneso-ate to give the ester (11) as a major product via the intermediate (12). Lithium aluminium hydride reduction again yielded presqualene alcohol (1). In each case the labelled synthetic alcohol, as its pyrophosphate, was incorporated by yeast subcellular particles into squalene in ca. 68 % yield. The minor synthetic isomers were not incorporated. 

Alkyl phenol ethoxylates have been over many years the workhorses as nonionic emulsifiers for emulsion polymerization. Depending on availability and price of buten and propen, nonyl (tripropylene)phenol ethoxylates or octyl (dibutylene) phenol ethoxylates have been very broadly used, whereas dodecyl (tetrapropylene or tributylene)phenol and tri tert-butylphenol ethoxylates were merely regarded as specialties. These aUcyl phenol ethoxylates can also be used as intermediates for the synthesis of anionic alkyl phenol ether sulphates. Sulphation by chlorosul-phonic acid or sulphur trioxide besides formation of the ether sulphate end group inevitably leads to certain amounts of ring sulphonation in the phenyl group, whereas amidosulphonic acid gives sulphonate-free aUcyl phenol ether sulphate ammonium salts. 

Large-pore mesoporous materials with enhanced textural characteristics (surface area, pore size distribution and pore volume) were obtained from a pH-adjusted synthesis with a surfactant mixture of hexadecyl- and dodecyltrimethylammonium salts in combination with mesitylene-swelling. This material was grafted with phenyl-alkoxysilanes and subsequently sulphonated. Nitrogen adsorption and multinuclear MAS NMR were performed to monitor the different synthesis steps. 

In the preparation of various unsaturated amides, the dianion of -phenyl-2-(phenyIsulphonylmethyl)propenamide (49) proved to be a versatile synthon. Borohydride reduction of alkylation products of the dianion occurred in high yield to afford moderate overall yields of ,B-unsaturated amides.The dianion of the corresponding phenyl sulphide alkylated poorly giving small amounts of oth a- and y-alkylation products, whereas the sulphone-ester corresponding to (49) was found to be labile under the deprotonation conditions. Compound (49) was also employed in the development of a general strategy for the synthesis of 3,4-epoxy-2-methylene-alkanoic acid amides (Scheme 29). ... 

Some aromatic sulphonic acids are decomposed on strong heating and hence must be protected during the Ullmann synthesis of sulphonated biaryls. For this purpose sulphonic acid groups are usually converted into the phenyl esters [21], e.g.. Fig. 10.9. Other examples are given in the Tables in Fanta s reviews of the Ulhnann synthesis of biaryls [22]. 

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