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8.1.26.1 Method 1: Synthesis of Bis(methylsulfanyl)methyllithium

DOI: 10.1055/sos-SD-008-00548

Nájera, C.; Yus, M.Science of Synthesis, (20068813.

The lithiated anion derived from bis(methylsulfanyl)methane 1 (Scheme 2) is formed by deprotonation with butyllithium at temperatures ranging between 78 and 0°C in tetrahydrofuran. This reagent 1 is alkylated with cyclohexene oxide,[‌6‌,‌7‌] and silylated or stannylated with chlorotrimethylsilane or chlorotrimethylstannane, respectively.[‌8‌‌11‌] It behaves also as a dianion equivalent when successive alkylations are carried out with two different alkyl halides in a one-pot process,[‌12‌‌15‌] and is applied to produce the phenanthrene nucleus.[‌13‌] A 2-deoxy-D-arabinohexopyranose 2 is prepared from tri-O-benzylated D-arabinitol 1,4-disulfate by alkylation of bis(methylsulfanyl)methyllithium (1) followed by hydrolysis, and unmasking of the dithioacetal functionality with N-bromosuccinimide.[‌14‌] The addition of intermediate 1 to tetrabenzyl-D-glucono-1,5-lactone gives 3, and is applied to the preparation of a precursor of valiolamine and related compounds (Scheme 2).[‌15‌,‌16‌] In the case of cyclohex-2-enone, only 1,2-addition is observed, whereas the corresponding α-silylated or α-stannylated derivatives give the corresponding Michael-type adducts.[‌11‌] Vinylic nucleophilic substitution takes place regioselectively at the β-position in the case of 3-alkoxycyclohex-2-enones (Scheme 2).[‌17‌‌19‌] The acylation of reagent 1 can be performed with 2,2-diethoxypropanenitrile in 49% yield.[‌20‌] The related bis(ethylsulfanyl)methyllithium,[‌21‌] obtained by deprotonation with lithium amide and alkylated with alkyl halides, has not been extensively used in organic synthesis, the exception being for the preparation of ketene thioacetals by condensation with aldehydes.[‌22‌]

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