Standard protocols report the selective deprotection of primary silyl ethers in the presence of secondary silyl ethers under acidic conditions, as exemplary shown in scheme 1, a reaction by Hartmann and Kalesse.[1]
Scheme 1: Selective deprotection of a primary silyl ether[1]
Numerous other examples can be found in the literature using numerous acidic reagents such as campher sulphonic acid,[2] para-tolylsulphonic acid[3] and even acetic acid[4] or $\ce{HCl}$.[5] Similar conditions can be used in the case of TIPS ethers.[citations needed]
I was wondering what the mechanism of this transformation looks like, and especially why it seems to be selective to primary silyl ethers. Answers that reference papers actually investigating the mechanism are preferred, but others are welcome, too.
List of abbreviations:
b.o.r.s.m: based on recovered starting material
Me: methyl
PPTS: pyridinium para-tolylsulphonate
TBS: tert-butyldimethylsilyl
TIPS: tetra-iso-propylsilyl
References:
[1] O. Hartmann, M. Kalesse, Org. Lett. 2012, 14, 3064. DOI: 10.1021/ol3011387
[2] Y. Mori, K. Yaegashi, H. Furukawa, J. Am. Chem. Soc. 1997, 119, 4557. DOI: 10.1021/ja9701523
[3] S. Kiyooka, K. A. Shahid, F. Goto, M. Okazaki, Y. Shuto, J. Org. Chem. 2003, 68, 7967. DOI: 10.1021/jo034901c
[4] B. H. Hart, S. K. Verma, H. Rapoport, J. Org. Chem. 2003, 68, 187. DOI: 10.1021/jo026499s
[5] A. B. Smith III, B. S. Freeze, I. Brouard, T. Hirose, Org. Lett. 2003, 5, 4405. DOI: 10.1021/ol035697i
[citations needed] I think, you get the picture, I’m not going to go looking for even more …