Oxathiane oxides, synthesis

Oxathiane dioxides lithiated 641 synthesis of 638, 647 Oxathiane oxides, synthesis of 352 Oxathiolane oxides, synthesis of 241 Oxaziridines 72, 254, 826 as optically active oxidizing agents 291 Oxazolidinones 826 Oxazolines 619, 788... 

Taking advantage of a tandem sulfoxide elimination-sulfenic acid addition approach to cyclic sulfoxides <1977J(P1)1574>, the synthesis of a number of novel 1,4-oxathiane oxides 229 and 230 based on the intramolecular addition of sulfenic acids to alkenes or alkynes tethered through an ether linkage has been reported (Equation 38) <20050BC404>. 

The synthesis of the 2-acyloxathianes 3 makes use of the fact that for stereoelectronic reasons1, electrophilic attack on conformationally locked 2-lithiated oxathianes 1 leads exclusively to equatorially substituted products 2. A subsequent oxidation step completes the synthesis. 

Oxathiane 2-oxides aie fonned by the oxidative ring expansion of 2-alkylthio-2-benzylthiolane 1-oxides brought about by [bis(trifluoroacetoxy)iodo]benzene. That the reaction is only successful with the (lR )-diastereoisomeis is attributed to chelation between the nucleophilic S and O atoms and the hypervalent iodine <99EJ0943>. A diazo-mediated thiolane ring expansion is the key step in a synthesis of the acenaphtho-[U-b][l,4]oxathiine system <99JCS(P2)755>. 

An asymmetric synthesis of mevalolactone in over 87% e.e. employs a 1,3-oxathiane as the chiral auxiliary (81TL2859). The reagent (818), easily prepared from (+)-pulegone (81TL2855), was metallated with u-butyllithium and the anion reacted with acetaldehyde. Oxidation of the diastereomeric mixture of alcohols to the ketone (819) and reaction of... 

Thermal decomposition of l,4-dihydro-2,3-benzoxathiin 3-oxides generates o-xylylenes which can be trapped by methyl 2-acetamidoacrylate yielding tetralin-based a-amino acids <04S558>. A phosphazene base [EtN=P(NMe2)2(N=P(NMe)2)3)] is used to generate the ylide from chiral oxathiane 74 in a two-step asymmetric synthesis of aziridines from tosylimines <04JOC1409>. 

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