Mild and efficient tetrahydropyranylation of alcohols and dehydropyranylation of THP ethers catalyzed by ferric perchlorate

KHSO4 as an Efficient Catalytic System for the Regiospecific Nitration of Phenols with Metal Nitrates

“…45 Very recently, we have reported the use of KHSO 4 as an efficient catalyst for the synthesis of 1,1-diacetates 43 and synthesis of 2-(cyclohexylamino)-6,7-dihydro-3-aryl-1H-indole-4(5H)-ones. 44 Even though the reaction proceeded with various metal nitrates, the time required for completion of the reaction was found to be less and the yields higher with Th(NO 3 ) 4 •5H 2 O. Phenols were treated with a metal nitrate and KHSO 4 in acetonitrile at reflux to afford o-nitrophenol as the exclusive product in satisfactory to good yields (Scheme 1). The scope and generality of the method are illustrated with several examples in Table 2 and all of them yielded the o-nitroproduct exclusively in good to excellent yields.…”

Ferric Perchlorate Catalyzed One‐pot Synthesis of 1,2,3,4‐Tetrahydro‐2‐pyrimidinones and ‐thiones: an Expedient Protocol for the Biginelli Reaction

“…8 Recently we have reported the ability of ferric perchlorate as a catalyst for alcoholysis and hydrolysis of epoxide, 9 transetherification of allylic and benzylic ethers, 10 aromatization of Hantzsh 1,4-dihydropyridines 11 and tetrahydropyranylation of alcohols and deprotection of THP ethers. 12 We have also recently reported on the catalytic activity of natural heulandite 13 and 12-tungstophosphoric acid 14 in Biginelli reaction. In this paper we wish to report ferric perchlorate as a mild, efficient, liable and relatively inexpensive catalyst for Biginelli three component one-pot synthesis of tetrahydropyrimidinones and their thiones.…”

Sulfonic acid-functionalized ordered nanoporous Na+-montmorillonite (SANM) as an efficient and recyclable catalyst for the tetrahydropyranylation and detetrahydropyranylation of alcohols and phenols

“…A wide variety of catalysts such as Sn IV (TPP)(OTf) 2 [2], polystyrene-supported GaCl 3 [3], silica sulfuric acid [4], solid silica based sulfuric acid [5], melamine trisulfonic acid [6], CuSO 4 Á5H 2 O [7], acetic acid assisted copper o-toluenesulfonate [8], Fe(ClO 4 ) 3 [9], Al(OTf) 3 [10], Sn IV (TNH 2 PP)(OTf) 2 @CMP [11], Al/AT-silica [12], {[K.18-crown-6]Br 3 } n [13], NbCl 5 [14], La(NO 3 [20] have been applied for tetrahydropyranylation of alcohols and phenols. However, many of these methods suffer from disadvantages such as long reaction times [9,10], unsatisfactory yields, harsh reaction conditions [8], expensive reagents [11,13,19], hazardous and toxic solvents or catalysts [17,18], tedious work-up, formation of polymeric by-products of the dihydropyran (DHP) and isomerization.…”

“…However, many of these methods suffer from disadvantages such as long reaction times [9,10], unsatisfactory yields, harsh reaction conditions [8], expensive reagents [11,13,19], hazardous and toxic solvents or catalysts [17,18], tedious work-up, formation of polymeric by-products of the dihydropyran (DHP) and isomerization. Therefore, introduction of efficient and economical catalysts that solves these drawbacks is desirable.…”