نتایج جستجو برای: aldol condensation

تعداد نتایج: 33583  

Journal: :Organic letters 2010
Jing Xu Eduardo J E Caro-Diaz Emmanuel A Theodorakis

An enantioselective formal synthesis of (-)-englerin A (1) is reported. Key to the strategy is a Rh-catalyzed [4 + 3] cycloaddition reaction between furan 10 and diazo ester 11 that, following an intramolecular aldol condensation, produces the tricyclic scaffold of englerin. This strategy also provides a rapid, efficient, and stereoselective access to the biologically significant core motif of ...

Journal: :The Journal of organic chemistry 2011
Chao Li Shanghui Tu Shuguang Wen Shan Li Junbiao Chang Feng Shao Xiaoguang Lei

A concise total synthesis of the G2/M DNA damage checkpoint inhibitor psilostachyin C is reported using a 1,4-addition-aldol condensation-ring-closing metathesis (RCM) strategy. Initial biological studies indicate that psilostachyin C could enhance the sensitivity of the HeLa cell toward camptothecin (CPT) treatment via the activation of the caspase-3 mediated apoptosis pathway.

Enayatollah Sheikhhosseini, Saleh Sadeghi Sayed Ali Ahmadi

An array of aromatic aldehydes with electron withdrawing groupunderwent crossed-Aldol condensation with cycloalkanone in the presence of catalytic amounts of DBSA under aqueous media to afford the corresponding α, ά-bis(substituted-benzylidene) cycloalkanones in good yields. The electronic effects on aromatic aldehydes could be observed. The present method is operationally simple and use of wat...

1998
Torsten Hoffmann Guofu Zhong Benjamin List Doron Shabat James Anderson Svetlana Gramatikova Richard A. Lerner Carlos F. Barbas

This paper describes the substrate specificity, synthetic scope, and efficiency of aldolase catalytic antibodies 38C2 and 33F12. These antibodies use the enamine mechanism common to the natural Class I aldolase enzymes. Substrates for these catalysts, 23 donors and 16 acceptors, have been identified. The aldol acceptor specificity is expected to be much broader than that defined here since all ...

2007
A Srikrishna

Two convenient methodologies have beendescribed for the enantiospecific synthesis of (–)-valeranone 1. The hydrindanone 12, obtained from the readily andabundantly available monoterpene (R)-carvone,has been converted into the ketoaldehyde 16via the alkene 15b. In anotherdirection the lactone 18, obtainedfrom the hydrindanone 12, has beenelaborated into the ketoaldehyde 16employing two methodolo...

2016
Shanshan Li Ning Li Wentao Wang Lin Li Aiqin Wang Xiaodong Wang Tao Zhang

Jet fuel range branched cycloalkanes with high density (0.82 g mL(-1)) and low freezing point (217-219 K) was first prepared by the solvent-free intramolecular aldol condensation of the trione from the hydrolysis of the alkylation product of mesityl oxide and 2-methylfuran (or the one-pot reaction of mesityl oxide, 2-methylfuran and water), followed by hydrodeoxygenation (HDO).

2010
Meng Guo

The title compound, C(17)H(15)ClO, was prepared from 3,4-dimethyl-benzaldehyde and 4-chloro-hypnone by Aldol condensation. The dihedral angle formed by the two benzene rings is 48.91 (8)°. Only van der Waals forces affect the packing.

Journal: :Organic letters 1999
M E Jung T W Johnson

[formula: see text] A novel pentacyclic polyhydroxylated sterol, xestobergsterol A (1a), has been synthesized in 24 steps and in good overall yield from stigmasterol 17. The key steps of the synthesis are the Breslow remote functionalization of the polyoxygenated steroid derived from 25 and the base-catalyzed epimerization-aldol condensation of the dione derived from 27.

Journal: :Chemistry 2006
Carl F Nising Ulrike K Ohnemüller Anne Friedrich Bernhard Lesch Jochen Steiner Hansgeorg Schnöckel Martin Nieger Stefan Bräse

Tetrahydroxanthenones, which can be easily prepared by a domino oxa-Michael aldol condensation, offer various possibilities for diastereoselective functionalization, giving access to the stereocontrolled synthesis of stereochemical triades or tetrades, which represent privileged structural motifs. In most cases, the relative stereochemistry was unequivocally established by crystal structure ana...

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