Aldehydes Methoxy methyllithium

Boronic esters, RB(OR )2 react with methoxy(phenylthio)methyllithium, LiCH(OMe)SPh, to give salts, which, after treatment with HgCl2, and then H2O2, yield aldehydes.This synthesis has been made enantioseiective, with high ee values (>99%), by the use of an optically pure boronic ester, for example ... 

An efficient process for one-carbon homologation to aldehydes is based on cyclic boronate esters.17 These can be prepared by hydroboration of an alkene with dibromobor-ane, followed by conversion of the dibromoborane to the cyclic ester. The homologation step is carried out by addition of methoxy(phenylthio)methyllithium to the boronate ester. The migration step is induced by mercuric ion. Use of enantioenriched boranes and boronates leads to products containing the groups of retained configuration.18... 

Aldehydes Alkyidimesitylborane. Chloro-methyltrimethylsilane. Diethyl[(2-tetrahy-dropyranyloxy)methylphosphonate. N,N-Dimethylchloromethyleniminum chloride. Dimelhyl(methylthio)sulfonium tetrafluom-borate. Methoxy(phenylthio)methyllithium. Methylthiomethyl p-tolyl sulfone. 1-Phen-ylthio-1 -trimethylsilylethylene. Tetrakis-(Iriphcnylphosphine)palladium. Thexyl-chloroborane-Dimethyl sulfide. 

Methoxy(phenylthio)methane and methoxy(phenylsulfonyl)methane are useful formyl anion equivalents for one-carbon homologation. For instance, addition of methoxy(phenylthio)methyllithium to ketones, followed by rearrangement of the adduct, provides a new method for the preparation of a-(phe-nylthio) aldehydes (equation 39). The reanangement is stereospecilic. This method has been used for the total synthesis of annelated furans such as (-)-)-euryfiiran, butenolides such as isodenninin and con-fertifolin and spirocyclic tetrahydiofurans and butenolides. ... 

Alkyl-l,3,2-dioxaborinanes, prepared by asymmetric hydroboration of prostereogenic olefins with monoisopinocampheylborane and subsequent removal of the chiral auxiliary, react with methoxy(phenylthio)methyllithium followed by treatment with mercuric(II) chloride, to give a-methoxyalkyl derivatives. Oxidation of these intermediates in a pH 8 phosphate buffer provides x-chiral aldehydes (method ) which are transformed by further oxidation into the corresponding a-chiral acids (method ) and by reduction into /i-chiral alcohols (method )14. 

The resulting 5-pentadecen-l-ol was oxidized with PCC to 5-pentadecenal. This aldehyde was then reacted with tris(methylthio)methyllithium, affording the corresponding a-hydroxy ortho(trithio)ether, which in turn was methylated in situ using NaH/DMF and Mel to obtain the methoxylated adduct, Fig. (11). Final HgC /HgO catalyzed hydrolysis afforded the desired methyl (Z)-2-methoxy-6-hexadecenoate. In this synthesis, the tris(methylthio)methyl group was used as the carboxy synthon. 

For example, treatment with p-toluenesulfonic acid in methanol affords dimethoxyacetals which can be further hydrolyzed to aldehydes (eq 2). Aldehydes are also available in one step by oxidation of the sulfide to the sulfoxide with m-chloroperbenzoic acid and hydrolytic workup (eq 2). Vinyl ethers are produced via a thermal elimination of benzenesulfenic acid (eq 3). Alternately, the anion formed from the addition of methoxy(phenylthio)methyllithium to aldehydes can be treated with carbon disulfide and iodomethane to form a xanthate which when treated with tributylstannane effects a radical reductive elimination to form (Z)- and ( )-enol ethers (eq 4). ... 

Aldehydes and ketones are efficiently converted to the ketene 0,S-acetals 75 by Peterson reaction with methoxy(phenylthio)(trimethylsilyl)methyllithium, which is... 

CuOTf-promoted elimination of thiophenol was exploited in two syntheses of 1-phenylthio-1,3-butadiene, one a C-C connective route from allyl bromide and bis(phenylthio)methyllithium, 4 and another from Croton-aldehyde (eq 49). A topologically analogous C-C connective strategy provides 2-methoxy-1-phenylthio-1,3-butadiene from acrolein (eq 50). - That the phenylthio rather than the methoxy substituent in 2-methoxy-1-phenylthio-1,3-butadiene controls the orientation of its Diels-Alder cycloadditions is noteworthy (eq 50). 

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