Proazaphosphatrane P(RNCH₂CH₂)₃N (R=Me, i‐Pr)‐Catalyzed Isomerization of Allylaromatics, Allyl Phenyl Sulfide, Allyl Phenyl Sulfone, and bis‐Allylmethylene Double Bond‐Containing Compounds

Abstract

Using a proazaphosphatrane catalyst, P(RNCH 2 CH 2 ) 3 N (R¼ Me, i-Pr), allylaromatics and allyl phenyl sulfide were selectively isomerized to the corresponding vinyl isomers in yields up to > 99% in CH 3 CN at 40 8C. Efficient transformation of allyl phenyl sulfone at ambient temperature afforded an isomerization/dimerization product in > 95% yield. Conjugation of bis-allylmethylene double bond-containing compounds gave the corresponding conjugated isomers for cis,cis-9,12-octadecadienol and its methyl ether in yields up to 97%, and desilylation/conjugation products were obtained from the catalytic reaction of the trimethylsilyl ether of cis,cis-9,12-octadecadienol. The reaction mechanism is discussed based upon the 1 H and 31 P NMR-monitored reactions in CD 3 CN or CH 3 CN under the reaction conditions.

Interactions of Verkade’s Superbase with Strong Lewis Acids: From Labile Mono- and Binuclear Lewis Acid–Base Complexes to Phosphenium Cations

“…Proazaphosphatranes, also referred to as Verkade’s bases, are exceptionally strong nonionic Brønsted bases of the general formula N­[CH 2 CH 2 N­(R)] 3 P, where R = H, Me, Bu i , Pr i , Bn, etc. − Pioneering work by the Verkade group has demonstrated these cagelike compounds to be valuable alternatives to inorganic bases in numerous base-catalyzed C–C, C–O, and C–N bond-forming reactions. − Proazaphosphatranes have also been reported to be superior in selectively deprotonating the cationic species L 2 RhH 2 + and L 2 CoH 2 + to generate L 2 RhH and L 2 CoH, highly active and robust catalysts in the hydrogenation of CO 2 . , Sneddon’s group and others have discovered that by the selective deprotonation of H 3 NBH 3 , a potentially useful hydrogen storage material, with Verkade’s base, structurally well-defined anionic borane-capped ammonia borane oligomers could be synthesized. , …”

Crown Ether Base: Highly Active, Regioselective and Reusable Catalytic Systems for Double Bond Migration in Allylic Compounds

“…N ‐allyl heterocycles, e. g., phenothiazine and indole or carbazole have been isomerized in the presence of t ‐BuOK, KOH, NaOH, BuOK, or NaH ,. To the best of our knowledge, there are only three papers in the literature reporting the double bond migration in allylaromatics (allyl phenyl sulfide, allyl phenyl sulfone, N ‐allylimidazole), N ‐allylimines, methyl linoleate, linoleyl alcohol and linoleyl trimethylsilyl ether catalyzed by a Verkade's super‐base ,,. Additionally, there are also four papers reporting the usage of the 18‐Crown‐6/KOH system,, (two of which were published by us) devoted to the isomerization of N ‐allylimidazole, N ‐allylimines to appropriate 2‐aza‐1,3‐diene, allyl‐phenyl‐ ether, sulfide, and selenide to appropriate 1‐propenyl derivatives .…”

A Facile, Convenient, and Green Route to (E)-Propenylbenzene Flavors and Fragrances by Alkene Isomerization

“…[28][29][30][31] Transition-metal catalysts generally isomerize allyl benzene flavors and fragrances to their phenylpropene analogues at moderate temperatures, but high E/Z selectivity remains a challenge, as reported for complexes of titanium, 32 iron, 33 nickel, 34 ruthenium, [35][36][37][38] rhodium, 39 and platinum, 40 where a compilation of such has been documented in a recent review. 41 Basic ligands, 42 bases grafted onto zeolite 43,44 and metals integrated into hydrotalcites, 35,45 have also been reported for the isomerization of these compounds. A platinum catalyst converts allyl benzenes at 50 °C into moderate yields (38-60%) and insufficient E/Z selectivity (63:37 to 97:3).…”

“…Methyl eugenol (4) is a minor constituent of bay leaf oil 15 and has been known to be an attractant 57 and fumigant 58 for fly species, in addition to containing antifungal properties 59 and being a food additive. Isomerization of methyl eugenol to methyl isoeugenol, which is a major constituent of pimento pseudocaryophyllus leaf oil, 20 has been reported in moderate to good yield, 40,42,60 and the product is used as food flavoring. 20 Elemicin ( 5) is a major constituent of elemi, nutmeg, and mace oil, 61,62 and (E)-isoelemicin is a minor con-stituent of rhizome 63 and Russian tarragon 64 oils.…”