Phenyl sulfoxide, isopropyl

Methyl m-tolyl (8), ethyl m-tolyl, methyl n-butyl and methyl n-propyl sulfoxides were obtained in 100% e.e. This method was less successful when applied to methyl phenyl sulfoxide (5% e.e.) or to methyl isobutyl and methyl ethyl sulfoxides (25% e.e.). No complexes were formed between methyl o-tolyl, methyl p-tolyl, methyl 2-butyl and methyl isopropyl sulfoxides so these compounds could not be resolved using 7. A crystal structure of the 1 1 complex formed between 7 and 8 revealed that the partners were linked by OH—OS hydrogen bonds in endless zig-zag chains23. More recently, 2-chloroethyl m-tolyl sulfoxide (9) has been resolved using 724. 

Asymmetric oxidation of formaldehyde dithioacetals with aqueous NaI04 was realized by Ogura et al. in the presence of a catalytic amount of BSA (0.005-0.02 mol equiv.) [96]. Under conditions the authors used, the starting sulfide was virtually insoluble in water (pH 9.2), and the best results were obtained at low concentrations of BSA. This result clearly indicates that the BSA/sulfide ratio is not the controlling factor of enantioselectivity. With this protocol, p-Tol-S-CH2-S-p-Tol could be transformed into monosulfoxide with 60% ee. The same protocol gave isopropyl phenyl sulfoxide with 60% ee. 

Figure 3 Inclusion compound of (S )-isopropyl phenyl sulfoxide by 1 (a) perspective view of crystals (b) sheet structure of 1 (c) CPK model. For clarity, phenyl groups of 1 and guest are unshaded and gray, respectively.

As mentioned in Section 2, isopropyl phenyl sulfoxide was included in the crystals of 1 with a high enantioselectivity of its (.S )-form. Generally, the inclusion compound of a sulfoxide was prepared by two methods (1) insoluble 1 was simply stirred in the presence of an alkyl phenyl sulfoxide and water (Method A sorption ) and (2) 1 was recrystallized in the presence of the sulfoxide (Method B ... 

The inclusion compounds of 1 and 2 were obtained by crystallization from an appropriate solvent system containing a guest (vide infra). (R) -1 hen y I <21 y cy I - (A1) - pheny lg I y cine (1) molecules self-assemble to form a layer structure and (.V)-isopropyl phenyl sulfoxide molecules are stereospecifically included in the void between the layers (Figure 4)7 A sheet structure was also observed in THF-included crystals of (/ )-(l-naphthyl)glycyl-(/ )-phenylglycine (2), which were formed by crystallization of 2 from a mixed solvent of tetrahydrofuran (THF) and... 

By Methods A and B, isopropyl phenyl sulfoxide was included in crystalline 1 with high ( -enantioselectivity (86 and 87% ee, respectively). Ethyl phenyl sulfoxide formed no inclusion compound by Method A, but the inclusion compound of its (5)-enantiomer was obtained by Method B. The inclusion crystal of (.V)-e(hyl phenyl sulfoxide is isostructural with that of (S)-isopropyl phenyl sulfoxide (Figure 3). As mentioned above, (6>ethyl phenyl sulfoxide was not included by Method A. The lack of one methyl group may make enthalpy (interaction with the inclusion cavity) and entropy disadvantageous in crystal packing to result in no inclusion of ethyl phenyl sulfoxide via Method A. 

Cyclopropyl phenyl sulfoxide (1) reacted with sodium azide to give S-cyclopropyl-S-phenyl-sulfoximide (2). (7 )-Cyclopropyl 4-tolyl sulfoxide reacted similarly with tosyl azide to afford (/ )-S-cyclopropyl-5 -(4-tolyl)-Al-tosylsulfoximide in 63% yield.Formation of a S-N bond was also observed on reaction of cyclopropanesulfonyl chloride 3 with trimethylamine and triethylamine in a mixture of dichloromethane and isopropyl alcohol giving the corresponding A. A -dialkylcyclopropanesulfonamide 4 the yields were, however, low (< 27%). ... 

Komori and Nonaka132,133 electrochemically oxidized methyl, isopropyl, n-butyl, isobutyl, r-butyl and cyclohexyl phenyl sulfides (108) and cyclohexyl p-tolyl sulfide (109) to their sulfoxides using a variety of polyamino acid-coated electrodes to obtain the range of e.e. values shown in parentheses. The highest enantiomeric purities were obtained using an electrode doubly coated with polypyrrole and poly(L-valine), an electrode which also proved the most durable of those prepared. 

Ac, acetyl AIBN, azobis(isobutanonitrile) All, allyl AR, aryl Bn, benzyl f-BOC, ferf-butoxycarbonyl Bu, Butyl Bz, benzoyl CAN, ceric ammonium nitrate Cbz, benzyloxycarbonyl m-CPBA, m-chloroperoxybenzoic acid DAST, diethylaminosulfur trifluoride DBU, l,8-diazabicyclo[5.4.0]undec-7-ene DCC, /V. /V - d i eye I oh e x y I c ar bo -diimide DCM, dichloromethyl DCMME, dichloromethyl methyl ether DDQ, 2,3-dichloro-5,6-dicyano-l,4-benzoquinone DEAD, diethyl azodicarboxylate l-(+)-DET, L-(+)-diethyl tartrate l-DIPT, L-diisopropyl tartrate d-DIPT, D-diisopropyl tartrate DMAP, 4-dimethylaminopyridine DME, 1,2-dimethoxyethane DMF, /V./V-dimethylformamide DMP, 2,2-dimethoxypropane Et, ethyl Im, imidazole KHMDS, potassium hexamethyldisilazane Me, methyl Me2SO, dimethyl sulfoxide MOM, methoxymethyl MOMC1, methoxymethyl chloride Ms, methylsulfonyl MS, molecular sieves NBS, N-bromosuccinimide NIS, /V-iodosuccinimide NMO, /V-methylmorpho-line N-oxide PCC, pyridinium chlorochromate Ph, phenyl PMB, / -methoxvbenzyl PPTs, pyridiniump-toluenesulfonate i-Pr, isopropyl Py, pyridine rt, room temperature TBAF, tetrabutylammonium fluoride TBS, ferf-butyl dimethylsilyl TBDMSC1, f-butylchlorodimethylsilane Tf, trifhioromethylsulfonyl Tf20, trifluoromethylsulfonic anhydride TFA, trifluoroacetic acid THF, tetrahydrofuran TMS, trimethylsilyl TPAP, tetra-n-propylammonium perruthenate / -TsOH. / -toluenesulfonic acid... 

The typical example of one-stage derivatization of amino acids is their treatment by isopropyl bromide in presence LiH with the formation of N-isopropy-lated isopropyl esters. Unfortunately, this reaction can take place only in high-boiling aprotic bipolar solvents like dimethyl sulfoxide (DMSO, = 189°C, RInonpoiar 90 18) tWs is a significant restriction for its application, in practice. A more important method is based on the reaction of amino acids with methyl or phenyl isothiocyanates with the formation of 3-methyl (phenyl) hydantoins ... 

Isopropyl 2-iodoxybenzoate is a useful reagent for the clean, selective oxidation of organic sulfides to sulfoxides [1127]. This reaction proceeds without overoxidation to sulfones and is compatible with the presence of the hydroxy group, double bond, phenol ether, benzylic carbon and various substituted phenyl rings in the molecule of organic sulfide. Duschek and Kirsch have reported that isopropyl 2-iodoxybenzoate in the presence of trifiuoroacetic anhydride can be used for the a-hydroxylation of p-keto esters at room temperature in THF [1128]. 

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