It is, but to a very minor extent. But like I said you have to make the protecting group much bigger than TMS. Usually 2-nitrobenzyl. One idea would be to just protect both groups, and then selectively deprotect the aromatic OH afterwards. Deprotecting OMe is never fun. It depends on how stable the rest of your molecule is. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment.
Notify me via e-mail if anyone answers my comment. This site uses Akismet to reduce spam. Learn how your comment data is processed. Previous Intramolecular Reactions of Alcohols and Ethers. Next Thiols And Thioethers. So how could we have prevented this from occurring? Summary: Protecting Groups For Alcohols This post barely scratches the surface of protecting groups for alcohols.
Advanced References and Further Reading Protection as silyl ethers: Protection of hydroxyl groups as tert-butyldimethylsilyl derivatives E. Corey and A. Marshall, Mathew M. Yanik, Nicholas D. Adams, Keith C. Ellis, and Harry R.
Chobanian Org. Davies, Clement L. Higginbotham, E. Treadgold J. Symmetrical alkoxysilyl ethers. A new class of alcohol-protecting groups. Preparation of tert-butoxydiphenylsilyl ethers John W.
Gillard, Rejean Fortin, Howard E. Morton, Christiane Yoakim, Claude A. Nelson, R. In organic synthesis, deprotection strategies are just as important as protection strategies! Ethers can also be used for alcohol protection.
Pyridinium p-toluenesulfonate. A mild and efficient catalyst for the tetrahydropyranylation of alcohols Masaaki Miyashita, Akira Yoshikoshi, and Paul A. This is of value when trying to protect an alcohol with several other delicate functional groups in the molecule.
Gunter Geibel Dr. It is substantially more stable than other acyl protecting groups. Ethoxyethyl ethers EE — Cleavage more trivial than simple ethers e. Acetyl Ac group is common in oligonucleotide synthesis for protection of N4 in cytosine and N6 in adenine nucleic bases and is removed by treatment with a base, most often, with aqueous or gaseous ammonia or methylamine.
Ac is too stable to be readily removed from aliphatic amides. Benzoyl Bz group is common in oligonucleotide synthesis for protection of N4 in cytosine and N6 in adenine nucleic bases and is removed by treatment with a base, most often with aqueous or gaseous ammonia or methylamine.
Bz is too stable to be readily removed from aliphatic amides. Acetals and Ketals — Removed by acid. Normally, the cleavage of acyclic acetals is easier than of cyclic acetals.
Orthoesters — Removed by mild aqueous acid to form ester, which is removed according to ester properties. LiAlH4, organolithium reagents or Grignard organomagnesium reagents. The group is widely used in oligonucleotide synthesis.
Orthogonal protection is a strategy allowing the deprotection of multiple protective groups one at a time each with a dedicated set of reaction conditions without affecting the other.
It was introduced in the field of peptide synthesis by Robert Bruce Merrifield in As a proof of concept orthogonal deprotection is demonstrated in a photochemical transesterification by trimethylsilyldiazomethane utilizing the kinetic isotope effect:. Due to this effect the quantum yield for deprotection of the right-side ester group is reduced and it stays intact.
Significantly by placing the deuterium atoms next to the left-side ester group or by changing the wavelength to nm the other monoarene is obtained. John D. For example, a Boc-protected amino group can be deprotected in acidic media, whereas a Fmoc-protected amino group can be deprotected under basic conditions. The presence of both protective groups in the same molecule therefore enables selective deprotection of one protected amino group for a further reaction while the second protected amino group remains untouched.
This is referred to as an orthogonal protecting group strategy. Not only is selectivity important, but the yields for the protection and deprotection steps must be high to avoid making the reaction sequence inefficient.
As a result, chemists in recent years prefer to design synthesis pathways that employ steps conducted under more selective reaction conditions, engineered to affect and convert only the specific desired functional group rather than harsher, less selective conditions that require protection for differentiation.
Another tactic is to employ reaction conditions under which the functional group "protects itself" temporarily, for example as an anion under basic conditions or a cation under acidic conditions.
These minimalist approaches can be summarized in the statements that, "the best protective group is no protective group", and "the best protective group is the one that isn't required".
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