4706-81-4Relevant articles and documents
Cleavage of tert-butyldimethylsilyl ethers by chloride ion
Farras, Jaume,Serra, Carme,Vilarrasa, Jaume
, p. 327 - 330 (2007/10/03)
A general method for the selective cleavage of tert-butyldimethylsilyl ethers in the presence of tert-butyldiphenylsilyl ones has been established using a combination of H2O and a concentrated solution of LiCl in DMF at 90°C. Since no acids, bases, reducing or oxidizing agents are used, the method seems to be very appropiate for the deprotection of TBDMS ethers in the presence of other sensitive functional groups.
A refined method for the removal of the methoxymethyl (MOM) protecting group for carbinols with acidic ion-exchange resin
Seto,Mander
, p. 2823 - 2828 (2007/10/02)
The methoxymethyl protecting group for carbinols is best removed from acid-sensitive substrates by hydrolysis in aqueous methanol using a cationic exchange resin (Dowex-50W).
Shape Selective Alkane Hydroxylation by Metalloporphyrin Catalysts
Cook, Bruce R.,Reinert, Thomas J.,Suslick, Kenneth S.
, p. 7281 - 7286 (2007/10/02)
A series of manganese and iron porphyrins with sterically protected pockets are shown to be shape selective alkane hydroxylation catalysts.With iodosobenzene as oxidant, good regioselectivity is observed for hydroxylation of alkanes at the least hindered methyl group by using the very sterically hindered (5,10,15,20-tetrakis(2',4',6'-triphenylphenyl)porphyrinato)manganese(III) acetate (MnTTPPP(OAc)) as catalyst; The moderately hindered (5,10,15,20-tetrakis(2',4',6'-trimethoxyphenyl)porphyrinato)manganese(III) acetate shows little selectivity toward terminal CH3 hydroxylation but does show enhancement for the adjacent, ω - 1, CH2 site.Primary selectivity is dependent on the size and shape of the alkane substrate, with more bulky substituents giving greater primary selectivity.Substituting pentafluoroiodosobenzene or m-chloroperbenzoic acid as oxidants yields similar selectivity, thus conclusively demonstrating metal based oxidation via a common intermediate for these three systems.In contrast, tert-butyl hydroperoxide or 2,2,2-trifluoroethanol solubilized pentafluoroiodosobenzene show no primary carbon selectivity, and reaction product ratios are independent of the metalloporphyrin catalyst; this demonstrates that the site of oxidation with these oxidants is not metal based.The iron porphyrin derivatives also show good primary selectivity, although to a lesser degree than with the Mn derivatives, proving that these oxidations too are metal based.The regioselectivities for alkane hydroxilation shown by TTPPP derivatives are comparable to or better than those found for some isozymes of cytochrome P-450 which are responsible for primary alcohol biosynthesis from steroids, fatty acids, and alkanes.