7446-84-6Relevant academic research and scientific papers
ELECTROPHILIC LACTONIZATION AS A TOOL IN ACYCLIC STEREOCONTROL; SYNTHESIS OF SERRICORNIN
Bartlett, Paul A.,Richardson, David P.,Myerson, Joel
, p. 2317 - 2327 (1984)
Several electrophilic lactonization procedures have been explored as a means of functionalizing olefinic carboxylic acids with relative asymmetric induction.Iodolactonization of δ,ε-unsaturated acids under conditions of thermodynamic control exhibits good
Stereoelectronic Effects: Perlin Effects in Thiane-Derived Compounds
Basche, Luis,Jung, Sebastian T.,Luy, Burkhard,Podlech, Joachim,Reinsperger, Tony
, (2020/04/15)
Stereoelectronic effects in thianes and thiane-derived sulfoxides, sulfones, sulfilimines, and sulfoximines were investigated by measuring 1JC,H coupling constants and by identification of normal and reversed Perlin effects, i.e., of differences in the coupling constants for equatorial and axial C–H bonds in the methylene groups of six-membered rings. The Perlin effects were correlated with results from natural bond orbital (NBO) analyses. NMR experiments were performed with conformationally restricted dimethyl- or tert-butyl-substituted derivatives, while the parent compounds were used for calculations. It turned out that the coupling constants are not only strongly influenced by stereoelectronic interactions with antiperiplanar C–H, C–C, C–O, and C–N bonds, but by the s character of the respective C–H bonds' carbon orbital as well.
Regioselective photochemical rearrangement of N-mesyloxylactams
Pichette, Simon,Aubert-Nicol, Samuel,Lessard, Jean,Spino, Claude
supporting information; experimental part, p. 1328 - 1335 (2012/04/05)
N-Mesyloxylactams can undergo ring contraction either by C-3 (usually observed) or C-5 migration. C-5 migration can occur when the C-3 migration product possesses ring strain, but it does not usually compete with C-3 migration. The greater preference for C-3 migration is due to the carbonyl oxygen atom, which greatly stabilizes the intermediate. Studies of the photochemical rearrangement of N-mesyloxylactams showed that the lone pair of the carbonyl oxygen atom, and not the degree of the substitution atthe migrating carbon atoms, is the governing factor in the regioselectivity of the reaction. Copyright
Microwave-assisted selective protection of glutaraldehyde and its symmetrical derivatives as monoacetals and -thioacetals
Flink, Heli,Putkonen, Tiina,Sipos, Attila,Jokela, Reija
experimental part, p. 887 - 890 (2010/03/24)
Six monoprotected acetals and -thioacetals of glutaradehyde and its symmetrical dimethyl derivatives were synthesized. Microwave-assisted heating proved to be a substantially more selective method for monoprotection than conventional heating. All reactions were efficient and only traces of diprotected material were formed.
Toward a total synthesis of okilactomycin. 1. A direct, enantiocontrolled route to the western sector
Paquette, Leo A.,Boulet, Serge L.
, p. 888 - 894 (2007/10/03)
A synthesis of the western half of the macrocyclic ring framework of the antitumor antibiotic okilactomycin is described. The strategy employed rests on an efficient synthesis of meso-2,4-dimethylglutaric anhydride and ensuing resolution via reaction with (S)-(-)-α-methylbenzylamine, diborane reduction, and selective crystallization. Following acid-catalyzed cyclization to (2S,4R)-2,4-dimethyl-δ-valerolactone, an acyclic stereocontrol strategy was adopted to achieve chain lengthening with appropriate incorporation of functionality. The sensitive aldehyde 2 was further homologated to β-keto ester 17 in a model reaction sequence performed to simulate its ultimate projected coupling to 3.
An Asymmetric Synthesis of Lactones from Cyclic Acid Anhydrides with Chiral Binaphthyldiamines
Kawakami, Yukio,Hiratake, Jun,Yamamoto, Yukio,Oda, Jun'ichi
, p. 693 - 698 (2007/10/02)
Asymmetric ring opening of the cyclic acid anhydrides cis-2,3-6 with the axially dissymmetric binaphthyldiamines (S)-1a-d and subsequent esterification gave diastereomeric mixtures of the amide-esters 7a-h.Successive reduction of the ester group and ring closure by hydrolysis afforded (-)-cis-2,4-dimethyl-δ-valerolactone (8, 92percent e.e.), (-)-mevalonolactone (9, 58percent e.e.)(+)-3-isopropyl-δ-valerolactone (10, 42percent e.e.), and (+)-2,3-methylene-γ-butyrolactone (11, 46percent e.e).Through kinetic resolution of the racemic anhydride trans-2, (-)-trans-2,4-dimethyl-δ-valerolactone (12) was yielded in a 74percent e.e., whose absolute configuration was established to be 2R,4R.
Esterification of Carboxylic Acids by Alcohols with 2-Chloro-1,3,5-trinitrobenzene as Condensing Agent
Takimoto, Seiji,Inanaga, Junji,Katsuki, Tsutomu,Yamaguchi, Masaru
, p. 1470 - 1473 (2007/10/02)
When mixtures of carboxylic acids or their sodium salts and alcohols were treatment with 2-chloro-1,3,5-trinitrobenzene in the presence of pyridine under mild conditions, the corresponding carboxylic esters were formed.The yields and the rates of the ester formation depended on the types of the acids and the alcohols used.
