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`Reference`

Discussion of a journal article relating to the Conversion of Molecule 15 to 16:

Ankala, S. V.; Fenteany, G. Tetrahedron Lett. 2002, 43, 4729-4732.

Ankala and Fenteany’s journal article presents a method for the selective deprotection of alkyl or aryl sillyl ethers. The technique was discovered in 2002. This discovery is essential for the conversion of compound 15 to compound 16. The use of cerium trichloride has the advantages of being inexpensive, non-toxic and as a mild Lewis-acid, a safer, milder reagent, than alternatives such as hydrogen fluoride. Compound 15 has two trimethylsilyl groups that require deprotection, however, the tert-butyl carbamate must be unaffected. Through the use of cerium trichloride, selective deprotection of the trimethylsilyl group can occur while leaving the tert-butyl carbamate which protects the nitrogen unaffected.

Citation #1: Gopinath, P.; Nilaya, S.; Muraleedharan, K. M. Org. Lett. 2011, 13, 1932-1935. The article anaylzes the usefulness of of SnCl3, as an excellent catalyst for chemoselective esterifications and selective removal of acid sensitive protecting groups such as Boc, THP, and TBMS in the presence of one another is demonstrated through suitable examples. This relates back to how Boc was not removed or ended up deprotecting NH and requires different deprotecting group from the ones that deprotect the TMS.

Citation #2: Wang, B.; Sun, H.; Sun, Z. J. Org. Chem. 2009, 74, 1781-1784. An efficient and chemselective deprotection for aryl siyl ethers using LiOAc as a bifunctional Lewis acid-base catalyst was described in this article. Acetate, epoxides, and aliphatic silyl ethers were preserved, whereas aryl TBS and TBDPS ethers can be differentiated in the reaction. This relates to the mechanism of deprotection that is applied in the synthesis of molecule 16 from 15.

Citation #3: Yan, H.; Oh, J.-S.; Song, C. E. Org. Biomol. Chem. 2011, 9, 8119-8121. A mild and efficient protocol for the deprotection of silyl ethers using KF in tetraethylene glycol is reported in this article. This is related to how the deprotection of the trimethylsilyl ether from the oxygen.