108329-93-7Relevant academic research and scientific papers
Asymmetric Michael Addition Reaction of Phosphorus-Stabilized Allyl Anions with Cyclic Enones
Denmark, Scott E.,Kim, Jung-Ho
, p. 7535 - 7547 (1995)
The asymmetric Michael addition reaction of chiraly modified P-allyl anions derived from enantiomerically ebriched 2-allyl-1,3,2-oxazaphosphorinane 2-oxides has been investigated with cyclic enones.The racemic 1,3,2-oxazaphosphorinane 2-oxide 3 has been shown to be extremely diastereoselective in the Michael addition to 5-, 6-, and 7-ring enones.With the enantiomerically enriched 2-allyl-1,3,2-oxazaphosphorinane 2-oxides, high regio- and diastereoselectivities (88-90percent diastereomeric excess) have been achieved in the Michael addition reaction of one of the diastereomers (cis series).The Michael reaction of the anions derived from the trans series were not diastereoselective (ca. 10percent diastereomeric excess).The origin of the addition selectivity can be rationalized by (1) consideration of the structure and conformational preferences of the allyl anion (parallel conformation, s-trans, no lithium contact), (2) conformational analysis of the 1,3,2-oxazaphosphorinane 2-oxide ring (chair, equatorial allyl group) and (3) assumption of a 10-membered ring transition state structure with lithium coordination of the enone.
Scalable Total Syntheses and Structure–Activity Relationships of Haouamines A, B, and Their Derivatives as Stable Formate Salts
Tsukamoto, Hirokazu,Nakamura, Saki,Tomida, Akito,Doi, Takayuki
, p. 12528 - 12532 (2020)
Haouamines A, B, and their derivatives were synthesized via Suzuki–Miyaura coupling and three key cyclization reactions as follows: the newly developed palladium(0)-catalyzed arylative cyclization of phenylalanine-derived alkyne–aldehydes with 2-bromoarylboronic acid (an “anti-Wacker”-type cyclization); BF3?OEt2-promoted Friedel–Crafts-type cyclization of symmetrical electron-rich aromatic rings adjacent to a tertiary allylic alcohol leading to the indeno-tetrahydropyridine skeleton; and (cyanomethyl)trimethylphosphonium iodide-mediated macrocyclization of amino alcohols to afford aza-paracyclophane precursors. The palladium-catalyzed reduction of mono- and di-triflate intermediates in the later stages enabled the alteration of both the position and number of hydroxyl groups on the C-ring. The instability of haouamine B was dramatically improved by salt formation with formic acid. An unambiguous evaluation of the cytotoxicity of the prepared haouamine derivative formates with and without hydroxyl groups at different positions on the C-ring indicated that the catechol structure in haouamine B produced weak cytotoxicity.
2-Carboxythioester-1,3-dithiane: A Functionalized Masked Carbonyl Nucleophile for the Organocatalytic Enantioselective Michael Addition to Enones
Massolo, Elisabetta,Brenna, Davide,Cozzi, Franco,Raimondi, Laura,Gaggero, Nicoletta,Benaglia, Maurizio
, p. 2716 - 2720 (2016)
An S-(2,2,2-trifluoroethyl) 1,3-dithiane-2-carbothioate has been successfully employed as acyl anion synthon in the organocatalytic enantioselective addition to enones promoted by quinine- and quinidine-derived tertiary/primary diamines. By proper selection of a co-catalyst and by optimization of the reaction parameters, convenient experimental conditions were found that allowed to obtain the highly functionalized products in up to 90% yield and 98% ee in short reaction times. These compounds, featuring selectively removable functionalities, proved to be versatile synthetic intermediates, which could be transformed into different derivatives without any erosion of the stereochemical integrity of the molecules.
Asymmetric synthesis of 3-substituted cyclohexylamine derivatives from prochiral diketones via three biocatalytic steps
Siirola, Elina,Mutti, Francesco G.,Grischek, Barbara,Hoefler, Sebastian F.,Fabian, Walter M. F.,Grogan, Gideon,Kroutil, Wolfgang
supporting information, p. 1703 - 1708 (2013/07/19)
Prochiral bicyclic diketones were transformed to a single diastereomer of 3-substituted cyclohexylamine derivatives via three consecutive biocatalytic steps. The two chiral centres were set up by a C-C hydrolase (6-oxocamphor hydrolase) in the first step and by an ω-transaminase in the last step. The esterification of the intermediate keto acid was catalysed by a lipase in the second step if possible. For two substrates the C-C hydrolytic step as well as the esterification could be run simultaneously in a one-pot cascade in an organic solvent. In one example, the reaction mixture of the first two steps could be directly subjected to bio-amination in an organic solvent without the need to change the reaction medium. Depending on the choice of the ω-transaminase employed and the substrate the cis- as well as the trans-diastereomers could be obtained in optically pure forms. Copyright
Conjugated additions of selenium containing enolates to enones - Enantioselective synthesis of δ-oxo-α-seleno esters and their facile transformations
Tiecco, Marcello,Testaferri, Lorenzo,Marini, Francesca,Sternativo, Silvia,Santi, Claudio,Bagnoli, Luana,Temperini, Andrea
, p. 543 - 551 (2007/10/03)
Titanium enolates derived from methyl phenylselenoacetate and other acetates bearing a selenium containing chiral auxiliary have been employed to bring about 1,4-addition reactions to enones. These reactions generate δ-oxo-α-seleno esters in good yields and with excellent regio- and diastereoselectivities. The results obtained clearly indicate that the Lewis acids, employed to activate the starting enones towards addition, greatly influence reactivity as well as the stereochemical outcomes of these reactions. TiCl4 complexation resulted in particularly efficient promotion of the 1,4-addition. Simple manipulations of the organoselenium moiety allowed some enantiomerically pure δ-oxo-α-camphorseleno esters to be transformed into the corresponding δ-oxo-α-hydroxy or δ-oxo-α-allyl esters or into trisubstituted tetrahydrofurans. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
Asymmetric Michael addition of malonate anions to prochiral acceptors catalyzed by L-proline rubidium salt
Yamaguchi, Masahiko,Shiraishi, Tai,Hirama, Masahiro
, p. 3520 - 3530 (2007/10/03)
L-Proline rubidium salt catalyzes the asymmetric Michael addition of malonate anions to prochiral enones and enals. This method can be applied to a wide range of substrates to give adducts with a predictable absolute configuration: (S)-adducts from (E)-enones/enals and (R)-adducts from cyclic (Z)-enones. Both the secondary amine moiety and the carboxylate moiety are critical for the catalytic activity and asymmetric induction. Varying the countercation also affects the reaction course. High enantiomeric excesses were attained when di(tert-butyl) malonate was added to (E)-enones in the presence of CsF. The stereochemistry of the Michael reaction indicates that asymmetric induction takes place via enantioface discrimination involving the acceptor α-carbon atom rather than the β-carbon atom.
ASYMMETRIC MICHAEL ADDITIONS OF ESTER ENOLATES TO ENANTIOMERICALLY PURE VINYLIC SULFOXIDES SYNTHESIS OF 3-SUBSTITUTED GLUTARATE ESTERS IN HIGH ENANTIOMERIC PURITY
Posner, Gary H.,Weitzberg, Moshe,Hamill, Terence G.,Asirvatham, Edward,Cun-heng, He,Clardy, John
, p. 2919 - 2929 (2007/10/02)
Various ester enolate ions add as Michael donors to enantiomerically pure Michael acceptor cycloalkenone sulfoxides 1a and 1b and unsaturated lactone sulfoxides 3a and 3b.The level of asymmetric induction in some cases is extraordinarily high (>=95percent
