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Corresponding author. Patrick H Dussault: ude. Received May 9; Accepted Jul 8. Summary Re VII oxides catalyze the acetalization, monoperoxyacetalization, monothioacetalization and allylation of hemiacetals. Results In the course of investigations into potential antischistosomal and antimalarial agents [ 16 — 17 ], we needed to prepare a number of 3-alkoxy-1,2-dioxolanes.
Table 1 Acetalization of hydroxy- and silyloxydioxolanes. R substrate product catalyst equiv PTSA 0. Open in a separate window.
Acetal formation As illustrated in Table 2 , we next investigated acetalization of tetrahydrofuranol 3 , tetrahydropyranol 4a and the O - t -butyldimethylsilyl ether of the latter 4b. Table 2 Transetherification of hemiacetals. Scheme 1. Table 3 Dimerization of hemiacetals.
Table 4 Optimization of acetalization conditions. Monothioacetal formation We next turned our attention to the synthesis of monothioacetals, a functionality important for carbonyl protection and as a precursor for oxycarbenium ions [ 21 — 22 ]. Table 5 Synthesis of monothioacetals. Scheme 2. Thioacetalization of hexanal with Re 2 O 7. Attempted reaction with nitrogen nucleophiles Perrhenate proved ineffective for catalyzing the formation of N , O -acetals Table 6. Table 6 Attempted synthesis of N , O -acetals. Allylation of hemiacetals Re 2 O 7 has been successfully applied to intramolecular Prins reactions of alkenes with reversibly generated hemiacetals [ 13 ], and we were curious about the potential for applications to intermolecular allylations.
Table 7 Allylation of hemiacetals. Transetherification of hydroperoxyacetals We were curious about the interactions of Re VII oxides with hydroperoxyacetals 1-alkoxyhydroperoxides , versatile intermediates available from ozonolysis of alkenes in alcoholic solvents [ 23 — 24 ]. Table 8 Alkoxide exchange within hydroperoxyacetals. Discussion All the reactions described appear to involve the intermediacy of perrhenate esters. Scheme 3.
Conclusion Perrhenates hold broad potential as catalysts for electrophilic activation of hemiacetals. Supporting Information Experimental details and detailed information, including references and spectral listings related to prepared molecules, are provided in Supporting Information File 1. File 1 Experimental details.
EP1316553A1 - Fragrances based on cyclic acetals - Google Patents
Click here to view. References 1. In: Ley S, editor. Stuttgart: George Thieme Verlag; Mol J C. Catal Today. Bellemin-Laponnaz S. Dussault P H, Ghorai P. Wiley; Rhenium VII Oxide.
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Volchkov I, Lee D. J Am Chem Soc. Xie Y, Floreancig P E. Angew Chem, Int Ed.
Org Lett. Chem Sci. Ghorai P, Dussault P H. Tadpetch K, Rychnosvky S D.
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J Org Chem. Pramanik S, Ghorai P.
Chem Commun. J Antimicrob Chemother. Dussault P H, Liu X. Angew Chem, Int Ed Engl. Edwards P, Wilkinson G. J Chem Soc, Dalton Trans. Protective Groups in Organic Synthesis. Crich D, Smith M. Bunnelle W H. Chem Rev. Bull Chem Soc Jpn. Tetrahedron Lett.
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