2- ethoxymethyl Chloride

Trimethylsilyl)ethoxymethyl chloride (SEMCl) [76513-69-4] M 166.7, b 57-59"/8mm, d 0.942, n 1.4350. Dissolve in pentane, dry (MgS04), evaporate and dist residual oil in a vac. Stabilise with lOppm of diisopropylamine. Store under N2in a sealed container in a refrigerator. [Lipshutz and Pegram Tetrahedron Lett 21 3343 I980. ... 

Finally, the carbamoyllithium 122 was prepared by tin-lithium transmetallation at —105 °C from the corresponding carbamoylstannane 121. This tin compound was prepared by addition of tri-n-butyltin lithium to an isocyanate followed by quenching with SEMC1 [2-(trimethylsilyl)ethoxymethyl chloride]. The functionalized intermediate 122 was acylated with the ester 123 to give the product 124 in a model study towards the synthesis of mycalamides (Scheme 33)115. 

The sodium or potassium alkoxide prepared from primary and secondary alcohols and sodium hydride or potassium hydride in THF reacts with 2-(trimethyl-silyi)ethoxymethyl chloride (SEMCl, bp 57-59 PC/1 kPa, HAZARD carcinogenic) to give the SEM ethers in good yield [Scheme 4.304]481 Alternatively, the alcohol can be alkylated with SEMC1 in the presence of f-PrjNEt in dichloro-methane at 4013 C [Scheme 4.305].257,525,555 Conversion of the SEMCl to the corresponding iodide in situ using tetrabutylammonium iodide accelerates the reaction ... 

The product from Step 1 (59 mmol) and Hunig s base (48 mmol) were dissolved in 75 ml CH2CI2, 2-(trimethylsilyl)ethoxymethyl chloride (70.8 mmol) added, and the mixture stirred 3.5 hours at 50 °C then 15 hours at ambient temperature. The mixture was poured into 200 ml NH4OAC solution, extracted with EtOAc, purified by flash chromatography using silica gel with hexane/EtOAc, 9 1, and 9.6 g product isolated. 

Primary, secondary and tertiary alcohols can be protected in good yield as their 2-(trimethylsil-yl)ethoxymethyl ethers (abbreviated SEM ethers) by reaction with 2-(trimethylsilyl)ethoxymethyl chloride (SEM-Cl) in dichloromethane in the presence of Pr 2NEt. The resultant ethers are stable to the conditions used to remove THP and TMS ethers (3 1 1 THF HOAc H20). Deprotection takes place on treatment with TBAF in THF at 45 °C. 

ALCOHOLS Allyltrimethylsilane. (1 5-Cyclooctadiene)bis(methyldiphenylphos-phine)iridium hexafluorophosphate. Guaiacylmethyl chloride. Levulinic acid. )3-(Trimethylsilyl)ethoxymethyl chloride. 2-(Tiimethylsilyl)ethyl chloroformate. 

Preparative Method involves reaction of triphenylphosphine with 2-(trimethylsilyl)ethoxymethyl chloride in benzene at gentle reflux for 18 h. Upon cooling, the resulting phosphonium salt can be recovered by filtration and purified by triturating with diethyl ether in 94% yield. ... 

---