- Sequencing cross-metathesis and non-metathesis reactions to rapidly access building blocks for synthesis
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The olefin cross-metathesis reaction has been sequenced with four common organic transformations in a one- or two-pot manner to rapidly access useful building blocks. Those reactions are: (1) phosphorus-based olefination (e.g., Wittig and Horner-Wadsworth-Emmons); (2) hydride reduction; (3) Evans propionate aldol reaction; (4) Brown allyl- and Roush crotyl-boration. The products of these reactions include stereodefined 2,4-dienoates, trans allylic alcohols, syn-propionate aldols, and chiral non-racemic homoallylic alcohols, respectively. Many of these intermediates have been carried further to natural products, demonstrating the utility of the methodology.
- Sirasani, Gopal,Paul, Tapas,Andrade, Rodrigo B.
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experimental part
p. 2197 - 2205
(2011/04/22)
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- Addition of kinetic boron enolates generated from β-alkoxy methyl ketones to aldehydes. Density functional theory calculations on the transition structures
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Herein we report that good to excellent levels of 1,5-anti stereoinduction are obtained in boron enolate aldol reactions of 1,2-syn β-alkoxy methyl ketones with achiral aldehydes, when the β-alkoxy protecting group is part of a benzylidene acetal. We have
- Dias, Luiz C.,Pinheiro, Sávio M.,de Oliveira, Vanda M.,Ferreira, Marco A.B.,Tormena, Cláudio F.,Aguilar, Andrea M.,Zukerman-Schpector, Julio,Tiekink, Edward R.T.
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supporting information; experimental part
p. 8714 - 8721
(2009/12/26)
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- The total synthesis and biological properties of the cytotoxic macrolide FD-891 and its non-natural (Z)-C12 isomer
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A total, stereoselective synthesis of the naturally occurring, cytotoxic macrolide FD-891 and of its non-natural (Z)-C12 isomer is described. Three fragments of the main carbon chain were stereoselectively prepared by using asymmetric aldol and allylation reactions as the key steps. The molecule was then assembled by using two Julia-Kocienski olefinations to connect the three fragments and a Yamaguchi reaction to close the macrolactone ring. Some specific biological properties (cytotoxicity, binding to tubulin) have been determined for both macrolides. The E configuration of the C12-C13 olefinic bond seems to be an important feature in determining the cytotoxicity but the precise biological mechanism of the latter still remains to be cleared.
- Garcia-Fortanet, Jorge,Murga, Juan,Carda, Miguel,Marco, J. Alberto,Matesanz, Ruth,Diaz, J. Fernando,Barasoain, Isabel
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p. 5060 - 5074
(2008/02/11)
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- Synthesis of the C1-C17 macrolactone of tedanolide
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The vinylogous Mukaiyama aldol reaction is a useful method to build up complex polyketide structures. It is successfully employed in the synthesis of the C1-C17 macrolactone of tedanolide, a highly cytotoxic marine natural product. These studies present a practical approach toward the total synthesis of tedanolide; it is pursued using the appropriate C13-C23 segment that is introduced by a pivotal aldol reaction to join both hemispheres.
- Hassfeld, Jorma,Eggert, Ulrike,Kalesse, Markus
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p. 1183 - 1199
(2007/10/03)
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- New Odorless Protocols for the Synthesis of Aldehydes and Ketones from Thiol Esters
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Dodecanethiol esters derived from odorless dodecanethiol proved to be suitable substrates for Pd-catalyzed reduction with triethylsilane, coupling with organozinc reagents, and coupling with terminal acetylenes.
- Miyazaki, Tohru,Han-Ya, Yuki,Tokuyama, Hidetoshi,Fukuyama, Tohru
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p. 477 - 480
(2007/10/03)
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