71699-33-7Relevant academic research and scientific papers
Stereoselective synthesis of a novel spiroacetal-dihydropyrone related to auripyrone
Perkins, Michael V.,Jahangiri, Saba,Taylor, Max R.
, p. 2025 - 2028 (2006)
A model spiroacetal-dihydropyrone related to that found in auripyrones A and B has been synthesised by a spiroacetalisation dehydration cascade. The route includes an unusual mutual kinetic diastereoselecting aldol reaction combining the key fragments.
Formation of (Z) Dialkylboron Enolates from Enolsilanes: Stereoconvergent Transmetallation and Diastereoselective Aldol Reactions
Duffy, Joseph L.,Yoon, Tehshik P.,Evans, David A.
, p. 9245 - 9248 (1995)
Transmetallation of (E) and (Z) enolsilanes using halodialkylborane (R2BX) reagents provides predominantly the (Z) dialkylboron enolate under mild conditions.These enolates afford high levels of syn selectivity in subsequent aldol reactions.
Lithium hexamethyldisilazide-mediated enolizations: Influence of triethylamine on E/Z selectivities and enolate reactivities
Godenschwager, Peter F.,Collum, David B.
supporting information; experimental part, p. 8726 - 8732 (2009/02/02)
Lithium hexamethyldisilazide (LiHMDS) in triethylamine (Et 3N)/toluene is shown to enolize acyclic ketones and esters rapidly and with high E/Z selectivity. Mechanistic studies reveal a dimer-based mechanism consistent with previous studies of
Stereoselective crossed aldol reaction via boron enolate generated from α-iodoketones and 9-BBN-H
Mukaiyama, Teruaki,Imachi, Shouhei,Yamane, Keiko,Mizuta, Masahiro
, p. 698 - 699 (2007/10/03)
Boron enolates were in situ generated smoothly by treating α-iodo ketones with 9-BBN-H, and aldols were produced in highly diastereoselective manner by successive reaction with various aldehydes at low temperature.
Stereoselective aldol reaction of α-seleno carbonyl compounds: Preparation of (Z)-α,β-unsaturated carbonyl compounds
Nakamura, Shuichi,Hayakawa, Toshinobu,Nishi, Tatsuya,Watanabe, Yoshihiko,Toru, Takeshi
, p. 6703 - 6711 (2007/10/03)
The aldol reaction of the titanium enolates of α-seleno esters in the presence of Ph3P or Ph3PO gave the products with high stereoselectivity favoring the syn isomers. Reaction of α-seleno ketones with TiCl4 in the presence of 2 equiv. of Et3N, and subsequently with aldehydes, gave the aldol products with high syn selectivity. The stereoselectivity in the aldol reaction of 3-pentanone also increased by using an excess amount of Et3N. The aldol products thus obtained from the α-seleno carbonyl compounds could be stereospecifically converted to (Z)-α,β-unsaturated carbonyl compounds by treatment with pyridine. (Z)-Alkylidenecyclopentanones were exclusively formed by treatment of the syn-aldol products with Et3N in the dark.
Diastereoselective aldol and reformatsky reactions of α-halo carbonyl compounds and aldehydes mediated by Titanium(II) Chloride
Kagayama,Igarashi,Shiina,Mukaiyama
, p. 2579 - 2585 (2007/10/03)
Highly diastereoselective aldol reactions of α-bromo ketones with several aldehydes were successfully carried out by using a combination of titanium(II) chloride and copper or sodium iodide in dichloromethane-pivalonitrile at low temperature. Similarly, Reformatsky reactions of α-bromo thioester with aliphatic aldehydes proceeded to afford β-hydroxy thioesters in good yields under mild conditions.
Catalytic, Diastereoselective Aldol Reactions Using Titanium(IV) Halides
Mahrwald, Rainer
, p. 919 - 922 (2007/10/02)
The aldol reaction in the presence of titanium halides is described.Good yields of aldols 10-17 were obtained even with only catalytic amounts of titanium tetrafluoride.The reactions were carried out in the absence of a base. - Keywords: Aldol reaction /
Ytterbium Trifluoromethanesulfonate Mediated Cross-Aldol Reaction between Ketones and Aldehydes
Fukuzawa, Shin-ichi,Tsuchimoto, Teruhisa,Kanai, Takeshi
, p. 2227 - 2232 (2007/10/02)
The cross-aldol reaction between a ketone and an aldehyde proceeded smoothly with threo diastereoselection favorably mediated by ytterbium trifluoromethanesulfonate and tertiary amine in diethyl ether or in dichloromethane.A ytterbium enolate was trapped
Diastereofacial Selectivity of Enolates
McCarthy, Peter A.,Kageyama, Masanori
, p. 4681 - 4686 (2007/10/02)
Results from our research in macrolide total synthesis prompted us to investigate ways of altering the diastereofacial selectivity of enolates without making major changes in the enolates' structure.The variation in the diastereofacial selectivity of enolates 7a-g derived from 3,4-syn-3-alkoxy-2,4-dimethylheptan-5-ones (5a-g) is presented.The parent enolate 7a was si-facial selective, while protecting the 3-hydroxyl group gave enolates that were re-facial selective (7b-g).Thus, without changing any chiral centers or backbone functionality, the diastereofacial selectivity of enolates can be varied or reversed.The implications of this finding to natural products synthesis are discussed.
ENANTIOSELECTIVE ALDOL CONDENSATIONS: THE USE OF KETONE BORON ENOLATES WITH CHIRAL LIGANDS ATTACHED TO BORON.
Paterson, Ian,Lister, M. Anne,McClure, Cynthia K.
, p. 4787 - 4790 (2007/10/02)
Aldol condensation between diethylketone and simple aldehydes using (Ipc)2BOTf/iPr2NEt in CH2Cl2 gives syn adducts in good ee (66-90percent) and with high diastereoselectivity (>=90percent).Other chiral dialkylboron triflate reagents examined give lower ees.
