New Jobs:

- Sr Material Chemist (Apple)

- Scientist (Pfizer)

- Sr Scientist (Ionis)

- Organic Chemist (Hudson)

Latest Internships:

- Sloan Kettering

  (Biomedical Sciences)

- Amgen

  (Process Engineering)



TBS Protection








Common Conditions (Protection):


TBS-Cl

TBS-Cl effectively protects primary and secondary alcohols (not tertiary). TBS-Cl reacts very slowly when used without basic activators (ex. imidazole or DMAP). DMF is the most common solvent.[1]





TBS-OTf

TBS-OTf is a very powerful silylating agent, and is capable of protecting primary, secondary, and teriary alcohols. The base is usually 2,6-lutidine and the solvent DCM.[1]






Common Conditions (Deprotection):


TBAF

Tetrabutylammonium fluoride (TBAF) is the most popular fluoride reagent for TBS deprotection. The basicity of fluoride can sometimes cause undesired side reactions.[1]





HCl

HCl effectively removes TBS groups. MeOH is often used as the solvent. Other acid sensitive functionalities may also be affected.[1]





Cs2CO3

Cs2CO3 (or K2CO3) is sometimes used to deprotect phenolic TBS ethers. Sometimes phenolic TBS ethers can be selectively deprotected in the presence of alkyl TBS ethers.[1][2]






References:


1) Kocienski, P. J.; Protecting Groups, 3rd Edition

2) Wuts, P. G. M.; Greene, T. W.; Greene's Protective Groups in Organic Synthesis, 4th Edition