7092-24-2Relevant academic research and scientific papers
Auxiliary controlled singlet-oxygen ene reactions of cyclohexenes
Fudickar, Werner,Vorndran, Katja,Linker, Torsten
, p. 10639 - 10646 (2007/10/03)
The photooxygenation of homochiral cyclohexene ketals, which are easily available from 2-cyclohexenone and l-tartrates, affords hydroperoxides and after reduction the corresponding allylic alcohols in good yields and high regioselectivities. This can be rationalized by electronic repulsions in a perepoxide intermediate and provides evidence for unfavorable 1,3 diaxial interactions with a dioxolane oxygen atom. Only low stereoselectivities were observed, due to the flexibility of the cyclohexene ring. However, the diastereomers could be separated and after cleavage of the auxiliary, 4-hydroxy-2-cyclohexen-1-one was isolated in enantiomerically pure form, which can serve as a building block for natural product synthesis.
Stereocontrolled synthesis of kelsoene by the homo-Favorskii rearrangement
Zhang, Liming,Koreeda, Masato
, p. 3755 - 3758 (2007/10/03)
(graph presented) (±)-Kelsoene (4) has been synthesized from 2,5-dihydroanisole in 16 steps in 12.5% overall yield. The key step involves a base-catalyzed reaction of γ-keto tosylate (5), which effects a homo-Favorskii rearrangement to 16 as well as the c
Stereoselectivity in the amination of chiral cyclohex-3-en-1-one ketals
Fioravanti, Stefania,Luna, Giuseppe,Pellacani, Lucio,Tardella, Paolo A.
, p. 4779 - 4786 (2007/10/03)
Optically active cyclohex-3-en-1-one ketals by photolysis of N3CO2-Et or N3C(OEt)NMs or by CaO induced α-elimination of NsONHCO2Et give diastereomeric aziridines (up to 72% yields, up to 60% d.e.). A simple HPLC separation allows to obtain practically pure aziridines. The conversion of the main product to the ketal of (R)-N-(ethoxycarbonyl)-β-aminocyclohexanone is also reported and a further oxidation directly gives a derivative of (R)-2-aminoadipic acid.
Nickel mdiated Double Bond formation from vic-Dibromides and Ethyl Magnesium Bromide
Malanga, Corrado,Aronica, Laura A.,Lardicci, Luciano
, p. 9189 - 9192 (2007/10/02)
vic-dibromides are quantitaively converted into alkenes by using a catalityc amount of NidppeCl2 in the presence of two molar equivalents of EtMgBr in THF.Stereochemical aspects of the reaction are given.
Selective Reversible and Irreversible Ligands for the κ Opioid Receptor
Cheng, Chen-Yu,Wu, Shou-Chien,Hsin, Ling-Wei,Tam, S. William
, p. 2243 - 2247 (2007/10/02)
(+/-)-(5β,7α,8β)-3,4-Dichloro-N-methyl-N-dec-7-yl>benzeneacetamide (14) and its (5α,7α,8β) diastereomer 15 have been synthesized from 1,4-cyclohexanedione monoethylene ketal (1) in 10 steps.Compound 14,
Hydroboration. 86. Convenient Conversion of Aldehydes and Ketones into the Corresponding Alkenes via Hydroboration of their Enamines. A Remarkably Simple Synthesis of Either (Z)- or (E)-Alkenes
Singaram, Bakthan,Rangaishenvi, Milind V.,Brown, Herbert C.,Goralski, Christian G.,Hasha, Dennis L.
, p. 1543 - 1549 (2007/10/02)
Aldehydes and ketones are converted into the corresponding alkenes via hydroboration of their enamines.Hydroboration of aldehyde enamines by 9-borabicyclononane (9-BBN), followed by methanolysis, affords the corresponding terminal alkenes in 75-90percent yields.Unsaturated aldehyde enamines produce the corresponding dienes under these conditions.Enamines derived from substituted cyclic ketones and heterocyclic ketones are readily accommodated in this reaction to afford the corresponding alkenes in very good yields.The synthesis of pure (Z)- or (E)-alkenes is readily achieved from the same acyclic ketone enamine by modification of the hydroboration-elimination procedure: (A) hydroboration by 9-BBN followed by methanolysis or (B) hydroboration by borane methyl sulfide (BMS) followed by methanolysis and hydrogen peroxide oxidation.Mechanistic rationale is provided.
Preparation of some N-substituted hexahydro-4H-azepin-4-ones
Laronze,Dridi,Sapi
, p. 881 - 884 (2007/10/02)
N-Substituted hexahydro-4H-azepin-4-ones were prepared from 2-cyclohexen-1-one via ozonolyse followed by reductive aminocyclization.
Synthesis of alkenes from enamines via hydroboration
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, (2008/06/13)
Alkenes are prepared by the hydroboration of enamines followed by an elimination reaction to form the alkene. This process has wide applicability and is useful for the stereospecific synthesis of [Z] isomers. It is preferred to use 9-borabicyclo[3.3.1 nonane as the hydroborating agent and to use methanol to catalyze the elimination reaction.
Through Space Interactions of Double Bonds by Photoelectron Spectroscopy
Lambert, Joseph B.,Xue, Liang,Bosch, Richard J.,Taba, Kalulu M.,Marko, Dale E.,et al.
, p. 7575 - 7579 (2007/10/02)
Steric effects between double bonds and remote polar substituents, previously manifested in nuclear magnetic resonance (NMR) spectra, are also evident in the ultraviolet photoelectron spectra (USP).An ether functionality was introduced at the 3-axial position of exo-methylenecyclohexane by means of acetal groups ( dimethyl and ethylene).The 3-axial ether group destabilizes the ? orbital on the double bond by 0.1-0.2 eV by a through space interaction (the 3-equatorial ether group by itself has little or no effect).This interaction apparently is responsible for the decreased proportion of 3-axial methoxyl observed by NMR spectroscopy.In contrast, 4-axial ether functionalities in cyclohexene show a slight stabilizing of the ? orbital by through bond electron withdrawal.These results also agree with the NMR observations, since the endocyclic double bond of cyclohexene permits a much larger proportion of 4-axial methoxyl.Ab initio calculations support the observations by paralleling the observed ?-orbital energies and by providing electron densities.Whereas 3-axial methoxyl clearly polarizes the double bond in methylenecyclohexane, 4-axial methoxyl has little or no effect on the electron densities of cyclohexene, even though methoxyl is closer to the endocyclic than to the exocyclic double bond.The NMR, UPS, and ab initio results provide an initial understanding of the three dimensionality of the ?-electron steric effects.
PREPARATION OF d,l-MEGAPHONE INTERMEDIATES
Hoye, Thomas R.,Kurth, Mark J.
, p. 4769 - 4772 (2007/10/02)
Chemistry related to the preparation of compounds 2 and 3, demonstrated intermediates in a synthesis of d,l-megaphone, is described.
