41343-18-4Relevant academic research and scientific papers
Formation of tetrahydrofuran derivatives and acetonylation of alkenes using carbon radicals derived from manganese(III) oxidation of diketene
Nishino, Hiroshi,Nguyen, Van-Ha,Yoshinaga, Shinji,Kurosawa, Kazu
, p. 8264 - 8271 (1996)
Oxidation of a mixture of diketene and a 1,1-diarylethene 1 with manganese(III) acetate dihydrate gave an equilibrium mixture of 5-hydroxy-2-pentanone 2 and a tetrahydrofuran-2-ol, which was subsequently dehydrated in glacial acetic acid to yield 4-penten-2-one 4 in good yield. A similar reaction in the presence of alcohols or amines afforded 2-alkoxy-2-methyltetrahydrofurans 5 or 3-acetyl-2-aminodihydrofurans 9 in moderate yields. Diketene reacted with manganese(III) acetate in the presence of nucleophiles, such as water and alcohols, to give a mixture of unconjugated manganese(III) enolate A and conjugated manganese(III) enolate B. Major products 4 and 5 were formed by the oxidation of the conjugated manganese(III) enolate B. Tetrahydrofurylideneacetates 3 and 7 derived from the unstable unconjugated enolate A were also obtained as minor products. The reaction pathways are discussed.
Copper-catalyzed aerobic aliphatic C-H oxygenation with hydroperoxides
Too, Pei Chui,Tnay, Ya Lin,Chiba, Shunsuke
supporting information, p. 1217 - 1225 (2013/07/26)
We report herein Cu-catalyzed aerobic oxygenation of aliphatic C-H bonds with hydroperoxides, which proceeds by 1,5-H radical shift of putative oxygen-centered radicals (O-radicals) derived from hydroperoxides followed by trapping of the resulting carboncentered radicals with molecular oxygen.
Methodology for in situ protection of aldehydes and ketones using trimethylsilyl trifluoromethanesulfonate and phosphines: Selective alkylation and reduction of ketones, esters, amides, and nitriles
Yahata, Kenzo,Minami, Masaki,Yoshikawa, Yuki,Watanabe, Kei,Fujioka, Hiromichi
, p. 1298 - 1307 (2014/01/06)
A methodology for selective transformations of ketones, esters, Weinreb amides, and nitriles in the presence of aldehydes has been developed. The use of a combination of PPh3-trimethylsilyl trifluoromethanesulfonate (TMSOTf) promotes selective transformation of aldehydes to their corresponding, temporarily protected, O,P-acetal type phosphonium salts. Because, hydrolytic work-up following ensuing reactions of other carbonyl moieties in the substrates liberates the aldehyde moiety, a sequence involving aldehyde protection, transformation of other carbonyl groups, and deprotection can be accomplished in a one-pot manner. Furthermore, the use of PEt3 instead of PPh 3 enables ketones to be converted in situ to their corresponding O,P-ketal type phosphonium salts and, consequently, selective transformations of esters, Weinreb amides, and nitriles in the presence of ketones can be performed. This methodology is applicable to various dicarbonyl compounds, including substrates that possess heteroaromatic skeletons and hydroxyl protecting groups.
Reversing the reactivity of carbonyl functions with phosphonium salts: Enantioselective total synthesis of (+)-centrolobine
Fujioka, Hiromichi,Yahata, Kenzo,Kubo, Ozora,Sawama, Yoshinari,Hamada, Tomohito,Maegawa, Tomohiro
supporting information; experimental part, p. 12232 - 12235 (2012/01/30)
Step saver: Carbonyl groups with lower reactivities can be transformed in the presence of more reactive ones by treatment with PPh3 (or PEt3) and TMSOTf prior to the reaction (see scheme; TMS=trimethylsilyl, Tf=trifluoromethanesulfonyl). This methodology can be applied to reduction and alkylation reactions, and enabled the short asymmetric total synthesis of (+)-centrolobine with the highest overall yield reported to date.
