Molecular sieves 5A as an acidic reagent: The discovery and applications
The first use of molecular sieves (MS) 5A as an acidic reagent is described. We observed the acidic property during a dehydration reaction of 2-methyl-4-phenyl-3-butyn-2-ol. The acidity was sufficient to introduce ethoxyethyl and methoxyisopropyl protecting groups into alcohols. Additionally, the employment of MS 5A improved the synthesis of 1,2,4-orthoacetyl-α-d- glucopyranose at the intramolecular transorthoesterification step. In the other step of the synthesis, MS 4A was also applied to demonstrate that the manipulation of MS simplified the total operations.
SYNTHESIS OF ISOCHROMANS VIA THE TITANIUM TETRACHLORIDE ASSISTED CYCLIZATION OF ACETALS OF PHENETHYL ALCOHOLS
This paper reports the preparation of five 3,4-dihydro-1H-2-benzopyrans in good yields via the TiCl4 promoted cyclization of acetals derived from phenethyl alcohols.
Mohler, Debra L.,Thompson, David W.
p. 2567 - 2570
(2007/10/02)
HCo(CO)4 AS AN ACID CATALYST IN VINYL ETHER REACTIONS
At room conditions in the presence of alcohols, HCo(CO)4 instead of being consumed by vinyl ethers, functions as an acid catalyst for acetal formation.
Freudenberger, John H.,Matsui, Yasushi,Orchin, Milton
p. 1811 - 1814
(2007/10/02)
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