2-(Trimethylsilyl)ethoxymethyl chloride

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| ImageFile = 2-(Trimethylsilyl)ethoxymethyl chloride.svg

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| Section1 = {{Chembox Identifiers

| CASNo = 76513-69-4

| CASNo_Ref = {{cascite|correct|CAS}}

| ChemSpiderID = 2006421

| EINECS = 278-483-4

| PubChem = 2724271

| StdInChI=1S/C6H15ClOSi/c1-9(2,3)5-4-8-6-7/h4-6H2,1-3H3

| StdInChIKey = BPXKZEMBEZGUAH-UHFFFAOYSA-N

| SMILES = C[Si](C)(C)CCOCCl

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| Section2 = {{Chembox Properties

| C=6 | H=15 | Cl=1 | O=1 | Si=1

| Appearance = Colorless liquid

| Density =

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| BoilingPt = {{convert|57|-|59|C|K}} (8 mmHg)

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| Section3 = {{Chembox Hazards

| GHSPictograms = {{GHS02}}{{GHS05}}

| GHSSignalWord = Danger

| HPhrases = {{H-phrases|226|314}}

| PPhrases = {{P-phrases|210|233|240|241|242|243|260|264|280|301+330+331|303+361+353|304+340|305+351+338|310|321|363|370+378|403+235|405|501}}

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2-(Trimethylsilyl)ethoxymethyl chloride (SEM-Cl) is an organochlorine compound with the formula C₆H₁₅ClOSi, which was developed by Bruce H. Lipshutz during his work on the synthesis of N-methylmaysenine. It is used to protect hydroxyl groups, which can be cleaved with fluoride in organic solvents selectively under mild conditions.{{cite journal | last1=Lipshutz | first1=Bruce H. | last2=Pegram | first2=Joseph J. | title=β-(Trimethylsilyl)ethoxymethyl chloride. A new reagent for the protection of the hydroxyl group | journal=Tetrahedron Letters | publisher=Elsevier BV | volume=21 | issue=35 | year=1980 | issn=0040-4039 | doi=10.1016/s0040-4039(00)78684-9 | pages=3343–3346}} Typically tetrabutylammonium fluoride and caesium fluoride can be used as deprotection reagents. Alternatives such as magnesium bromide,{{cite journal | last1=Vakalopoulos | first1=Alexandros | last2=Hoffmann | first2=H. M. R. | title=Novel Deprotection of SEM Ethers: A Very Mild and Selective Method Using Magnesium Bromide | journal=Organic Letters | publisher=American Chemical Society (ACS) | volume=2 | issue=10 | date=2000-04-21 | issn=1523-7060 | doi=10.1021/ol0057784 | pages=1447–1450| pmid=10814469 }} lithium tetrafluoroborate and boron trifluoride etherate were also developed to deprotect SEM group.{{cite book | last1=Katritzky | first1=A.R. | last2=Kirby | first2=G.W. | last3=Meth-Cohn | first3=O. | last4=Rees | first4=C.W. | title=Comprehensive Organic Functional Group Transformations | publisher=Elsevier Science | issue=v. 4 | year=1995 | isbn=978-0-08-042325-8 | url=https://books.google.com/books?id=0RQEsfYCuBcC&pg=PA176 | access-date=2021-10-25 | page=176}}