66248-02-0Relevant academic research and scientific papers
Gold-catalyzed formal [4π+2π]-cycloadditions of tert-butyl propiolates with aldehydes and ketones to form 4H-1,3-dioxine derivatives
Karad, Somnath Narayan,Chung, Wei-Kang,Liu, Rai-Shung
supporting information, p. 13004 - 13007 (2015/08/06)
Gold-catalyzed formal hetero-[4π+2π] cycloadditions of tert-butyl propiolates with carbonyl compounds proceeded efficiently to yield 4H-1,3-dioxine derivatives over a wide scope of substrates. With acetone as a promoter, gold-catalyzed cycloadditions of these propiolate derivatives with enol ethers led to the formation of atypical [4+2]-cycloadducts with skeletal rearrangement.
Pd-catalyzed carbonylation of diazo compounds at atmospheric pressure: A catalytic approach to ketenes
Zhang, Zhenhua,Liu, Yiyang,Ling, Lin,Li, Yuxue,Dong, Yian,Gong, Mingxing,Zhao, Xiaokun,Zhang, Yan,Wang, Jianbo
supporting information; experimental part, p. 4330 - 4341 (2011/06/21)
The carbonylation of carbenes through catalytic cycles is highly desirable due to the importance of ketene-mediated reactions in organic synthesis. In this investigation, a highly efficient and mild catalytic approach toward ketene intermediates has been developed based on Pd-catalyzed carbonylation of diazo compounds with CO. When α-diazocarbonyl compounds or N-tosylhydrazone salts are heated in the presence of a palladium catalyst under atmospheric pressure of CO, ketene intermediates are formed in situ, where they undergo further reactions with various nucleophiles such as alcohols, amines, or imines. The Pd-catalyzed tandem carbonylation-Staudinger cycloaddition gives β-lactam derivatives in good yields with excellent trans diastereoselectivity. The results from DFT calculation on the reaction mechanism suggest that Pd is involved in the [2 + 2] cycloaddition process and affects the diastereoselectivity of the β-lactam products by assisting isomerization of the addition intermediate. On the other hand, the acylketenes generated from the Pd-catalyzed carbonylation of α-diazoketones react with imines in a formal [4 + 2] cycloaddition manner to afford 1,3-dioxin-4-one derivatives. This straightforward carbonylation provides a new approach toward highly efficient catalytic generation of ketene species under mild conditions.
Stereoselective control in the Staudinger reactions involving monosubstituted ketenes with electron acceptor substituents: Experimental investigation and theoretical rationalization
Qi, Hengzhen,Li, Xinyao,Xu, Jiaxi
experimental part, p. 2702 - 2714 (2011/05/19)
The stereoselectivity of the Staudinger reactions involving monosubstituted ketenes with electron acceptor substituents was investigated experimentally by determination of the product stereochemistry and theoretically via DFT calculations. The results indicate that imines preferentially attack the less sterically hindered exo-side of the ketenes to generate zwitterionic intermediates. Subsequently, for cyclic imines, the intermediates undergo a conrotatory ring closure directly to produce β-lactams, while for linear imines, the imine moiety of the intermediates isomerizes to more stable intermediates, which further undergo a conrotatory ring closure to afford trans-β-lactams. The steric hindrance and the isomerization, rather than the torquoelectronic effect, play crucial roles in controlling the stereoselectivity in the practical Staudinger reactions involving monosubstituted ketenes with electron acceptor substituents, although the unaccessible borylketene with a powerful electron acceptor group controls the stereoselectivity torquoelectronically, in theory.
Expeditious synthesis of 2,3,6-trisubstituted 2 H -1,3-oxazin-4(3 H)-ones via the tertiary amine-induced reaction of 2-diazo-3-oxoalkanals and imines under mild conditions
Qi, Hengzhen,Zhang, Jiantao,Xu, Jiaxi
, p. 887 - 894 (2011/05/05)
A series of 2,3,6-trisubstituted 2H-1,3-oxazin-4(3H)-one derivatives were conveniently synthesized in satisfactory to good yields by the reaction of imines with 2-diazo-3-oxoalkanals in the presence of a catalytic amount of a tertiary amine during several seconds under mild condition. Different bases and -diazo - dicarbonyl compounds were also evaluated and a reaction mechanism is proposed. Compared with the corresponding thermal- and photo-induced- reactions, the current method is a metal-free, mild, highly regioselective, and more efficient approach for the synthesis of 2H-1,3-oxazin-4(3H)-one derivatives. Georg Thieme Verlag Stuttgart - New York.
1,3-Oxazines and Related Compounds. XIII. Reaction of Acyl Meldrum's Acids with Schiff Bases Giving 2,3-Disubstituted 5-Acyl-3,4,5,6-tetrahydro-2H-1,3-oxazine-4,6-diones and 2,3,6-Trisubstituted 2,3-Dihydro-1,3-oxazin-4-ones
Yamamoto, Yutaka,Watanabe, Yukiyoshi,,Ohnishi, Shuhei
, p. 1860 - 1870 (2007/10/02)
The reaction of Schiff bases (2) with various acyl Meldrum's acids (1) were investigated.Refluxing of 1 and 2 in benzene caused an exchange reaction of the acetone moiety of 1 with the Schiff base moiety through the intermediate acylketenes 11 formed in s
1,3-Oxazines and Related Compounds. XIV. Facile Synthesis of 2,3,6-Trisubstituted 2,3-Dihydro-1,3-oxazine-5-carboxilyc Acids and 1,4-Disubstituted 3-Acyl-β-lactams from Acyl Meldrum's Acids and Schiff Bases
Yamamoto, Yutaka,Watanabe, Yokiyoshi
, p. 1871 - 1879 (2007/10/02)
Simple preparation of 2,3,6trisubstituted 2,3-dihydro-1,3-oxazine-5-carboxylic acids (4) and 1,4-disubstituted 3-acyl-β-lactams (5) from acyl Meldrum's acids and Schiff bases were carried out.2,3-Disubstituted 5-acyl-3,4,5,6-tetrahydro-2H-1,3-oxazine-4,6-
Reaction of 2,2-dimethyl-1,3-dioxin-4-ones with Imines, Carbodiimides, and Isocyanates
Sato, Masayuki,Ogasawara, Hiromichi,Kato, Tetsuzo
, p. 2602 - 2608 (2007/10/02)
The ring transformation of 2,2-dimethyl-1,3-dioxin-4-ones (1) to nitrogen heterocycles was studied.Heating of 1 whith imines such as Schiff bases gave rise to cycloadducts of imines to acylketenes (2), i.e., 3,4-dihydro-1,3-oxazin-4-one derivatives
CHEMISTRY OF OXALYL DERIVATIVES OF METHYL KETONES. XXVI. REACTION OF 5-ARYL-2,3-DIHYDRO-2,3-FURANDIONES WITH SCHIFF BASES
Andreichikov, Yu. S.,Ionov, Yu. V.
, p. 2154 - 2158 (2007/10/02)
5-Aryl-2,3-dihydro-2,3-furanediones react with Schiff bases formed by aromatic aldehydes to give 3-substituted 2,6-diaryl-2,3-dihydro-4H-1,3-oxazin-4-ones.The Schiff bases obtained from acetophenone open ring of 5-aryl-2,3-dihydro-2,3-furanediones, forming N-aryl-Nα-styrylaroylpyruvamides.
