652132-98-4Relevant academic research and scientific papers
Synthesis and Expansion of Bicyclic Enol Ether: A Probable Precursor for the Synthesis of Macrolide (±)-Pyrenophorin
Costa, Maísa B.,Martins, Marcos P.,de Araújo, Hugo C.,Resck, Inês S.
, p. 74 - 78 (2017/12/08)
A convenient procedure for the synthesis and expansion of bicyclic rings has been developed for the production of probable precursors of non-racemic pyrenophorin, an antibiotic dilactone. The major highlight for this new synthetic methodology came from the use of a readily available reagent of easy manipulation, 9-oxabicyclo[3.3.1]nonane-2,6-diol, for the preparation of the bicyclic intermediate, which sequentially was subjected to oxidative cleavage with butyl nitrite resulted in an isomeric mixture, a dioximedilactone and diisoxazoledilactone.
Transannular O -heterocyclization: A useful tool for the total synthesis of Murisolin and 16,19- cis -Murisolin
Persich, Peter,Kerschbaumer, Julia,Helling, Sandra,Hildmann, Barbara,Wibbeling, Birgit,Haufe, Günter
supporting information, p. 5628 - 5631 (2013/01/15)
Transannular O-heterocyclization is applied as a key step in a total synthesis. This highly stereoselective and metal-free transformation introduces four stereocenters in one step. It was chosen to be the pivotal step in the synthesis of Murisolin and 16,19-cis-Murisolin, two annonaceous acetogenins. The efficiency of this synthesis is further illustrated by a stereodivergent late-stage separation of both synthetic routes.
Highly active and green aminopropyl-immobilized phosphotungstic acid on mesocellular silica foam for the O-heterocyclization of cycloocta-1,5-diene with aqueous H2O2
Gao, Ruihua,Zhu, Quanjing,Dai, Wei-Lin,Fan, Kangnian
experimental part, p. 702 - 708 (2011/05/12)
The heteropoly phosphotungstic acid, H3PW12O 40 (HPW), was successfully immobilized on the surface of MCF, SBA-15 and MCM-41 by means of chemical bonding to aminosilane groups. The as-obtained materials were characterized by N2 sorption, TEM, XRD, FT-IR, 13C-, 29Si-, 31P-MAS NMR and XPS. Characterization results suggest that the surface area decreased after grafting amino groups to silica. The as-prepared HPW-NH2-MCF is highly efficient in the O-heterocyclization of cycloocta-1,5-diene (COD) to 2,6-dihydroxy-9-oxabicyclo[3.3.1] nonane (1) and 2-hydroxy-9-oxabicyclo [3.3.1] nonane-6-one (2) with a COD conversion of 100% and (1 + 2) selectivity up to 98%. It is worth mentioning that this material could be reused six times without any significant loss of activity and selectivity. The good stability can be attributed to the strong interaction between the amino groups on the surface of MCF and HPW anions. The Royal Society of Chemistry.
Synthesis of enantiopure 9-oxabicyclononanediol derivatives by lipase-catalyzed transformations and determination of their absolute configuration
Hegemann, Klaus,Froehlich, Roland,Haufe, Guenter
, p. 2181 - 2192 (2007/10/03)
Mixtures of endo,endo-9-oxabicyclo[4.2.1]nonane-2,5-diol (meso-2) and endo,endo-9-oxabicyclo[3.3.1]nonane-2,6-diol [(±)-3] were prepared from cycloocta-1,5-diene (1) upon 09174874200 treatment with peracids by transannular O-heterocyclization and subsequent saponification of the formed diol monoesters such as (±)-4 and (±)-5. The corresponding diacetates, meso-6 and (±)-7, were formed by acetylation of either meso-2 and (±)-3 or (±)-4 and (±)-5 with acetic anhydride/pyridine. These diacetates were enantioselectively hydrolyzed by microbial enzymes such as the lipases from Candida antarctica (CAL) or Candida rugosa (CRL). The corresponding enantiomers were formed by lipase-catalyzed acetylation of the diols meso-2 and (±)-3 with vinyl acetate. The skeletal isomers can also be separated in this way because the enantiopure monoacetates 4 were formed from the meso-compounds 2 or 6, while one enantiomer of the racemic diacetate (±)-7 [or the diol (±)-3] was transformed into the enantiopure diol 3 (or the enantiopure diacetate 7, respectively) via the corresponding enantiomers of the monoacetate 5. The other enantiomer remained untouched in both cases. The lipases reacted enantioselectively to give the R isomer. Cycloocta-1,5-diene (1) was also used to synthesize 2-oxa-6-thiatricyclo[3.3.1. 13,7]decane-4,8-diol [(±)-11] in a four-step sequence. This racemic diol was also acetylated selectively (R isomer) with vinyl acetate and CRL. Reductive desulfuration of (±)-11 gave exo,exo-9-oxabicyclo[3.3.1]nonane-2,6-diol [(±)-12], which was acetylated selectively (S isomer) with CRL under the same conditions. The similarity in size and particularly in shape is responsible for the observed stereoselectivity of the lipases for the racemic endo,endo compounds (±)-3 and (±)-7 on the one hand and the exo,exo compound (±)-12 on the other hand. The absolute configuration and crystal packing of the products was determined by X-ray structural analysis. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
Synthesis of (-)-xialenon A by enantioselective α-deprotonation- rearrangement of a meso-epoxide
Hodgson, David M.,Galano, Jean-Marie,Christlieb, Martin
, p. 9719 - 9728 (2007/10/03)
The first total synthesis of (-)-xialenon A was achieved via enantioselective transannular desymmetrisation of a substituted cycloctene oxide using an organolithium/(-)-α-isosparteine combination. Oxidation of the resulting bicyclo[3.3.0]octanol gave an enone which underwent stereoselective conjugate allylation; subsequent α′-hydroxylation on the more hindered face of a derived enone using hypervalent iodine chemistry led to the natural product.
Selectivity of Candida rugosa lipase in simultaneous separation of skeletal isomers, desymmetrization, and kinetic racemate cleavage of 9-oxabicyclononanediols
Hegemann, Klaus,Schimanski, Holger,H?weler, Udo,Haufe, Günter
, p. 2225 - 2229 (2007/10/03)
The diols 2 and 3, available in one step from cycloocta-1,5-diene, are selectively acetylated at the (R)-centers using Candida rugosa lipase to give the corresponding enantiopure compounds. In contrast, the (S,S)-enantiomer of 11 is transformed under iden
