Mosher Amides: Determining the Absolute Stereochemistry of Optically-Active Amines

2008 ◽  
Vol 85 (5) ◽  
pp. 698 ◽  
Author(s):  
Damian A. Allen ◽  
Anthony E. Tomaso ◽  
Owen P. Priest ◽  
David F. Hindson ◽  
Jamie L. Hurlburt
Keyword(s):  
Optically Active ◽  
The Absolute ◽  
Absolute Stereochemistry

Stereospecific synthesis of hexahydrobenzopyrroloisoquinoline and tetrahydrobenzisoquinoline derivatives

1984 ◽  
Vol 37 (4) ◽  
pp. 819 ◽  
Author(s):  
E Gellert ◽  
N Kumar
Keyword(s):  
Amino Acids ◽  
Metal Hydride ◽  
Optically Active ◽  
Stereospecific Synthesis ◽  
Hydride Reduction ◽  
The Absolute ◽  
Absolute Stereochemistry

New optically active hexahydrobenzopyrroloisoquinoline and tetrahydrobenzisoquinoline derivatives have been synthesized. Metal hydride reduction of the cyclic amino ketones, prepared by mild Friedel-Crafts type intramolecular acylation of N-naphthalenylmethyl amino acids, yielded pairs of diastereoisomeric alcohols. The absolute stereochemistry and some features of the n.m.r. spectra of hexahydrobenzopyrroloisoquinolines, tetrahydrobenzisoquinoline and those of their intermediates are discussed.

Terpenoid chemistry. XXI. ( - )-Epingaione, ( - )-Dehydrongaione, ( - )-Dehydroepingaione, and ( - )-Deisopropylngaione, toxic furanoid sesquiterpenoid ketones from Myoporum deserti

1973 ◽  
Vol 26 (2) ◽  
pp. 375 ◽  
Author(s):  
WD Hamilton ◽  
RJ Park ◽  
GJ Perry ◽  
MD Sutherland
Keyword(s):  
Essential Oils ◽  
Optically Active ◽  
Aqueous Alkali ◽  
Liver Pathology ◽  
Liver Lesions ◽  
Literature Report ◽  
The Absolute ◽  
Absolute Stereochemistry

The isolation and properties of four furanoid sesquiterpene ketones from various specimens of the stock-poisoning shrub Myoporum deserti are described. (-)-Epingaione [(-)-(1S,4S)-β-(4,8-dimethyl-6-oxo-1,4- epoxynonyl)furan] may be epimerized to (-)-ngaione either thermally or by base. (-)-Dehydrongaione [(-)-(1S,4R)-β-(4,8-dimethyl-6-oxo-1,4- epoxynon-7-enyl)-furan] is hydrogenated to (-)-ngaione and is equilibrated either thermally or by base with the unconjugated isopropenylic non-8-enyl isomer and (-)-dehydroepingaione [the (1S,4S)- diastereomer], which is hydrogenated to (-)-epingaione. Treatment of dehydrongaione and its epimer with aqueous alkali yields (-)- deisopropylngaione and its epimer by a retroaldol reaction. ��� The argument used by Matsuura1 to deduce the absolute stereochemistry of (+)-ngaione (ipomeamorone) is invalid since, contrary to the literature report, the ipomic lactone obtained from the oxidation of ngaione is not optically active. ��� Specimens of M. deserti have been found which yield essential oils containing each of the four furanoid ketones (-)-ngaione, (-)- epingaione, (-)-dehydrongaione, and (-)-dehydroepingaione free or virtually free from the others. The presence of a few percent of (-)- deisopropylngaione in one (dehydrongaione-rich) M. deserti oil has been demonstrated. ��� (+)-Ngaione, (-)-epingaione, and a mixture of (-)-dehydrongaione and (-)-dehydroepingaione all cause the typical (-)-ngaione liver pathology when injected intraperitoneally into mice. M. deserti plants containing the latter three ketones must be regarded as potentially capable of inducing M. deserti poisoning in stock. A mixture of (-)- deisopropylngaione and (-)- deisopropylepingaione causes both kidney and liver lesions.

Absolute Stereochemistry of (-)-Wieland-Miescher Ketone as Established by the X-ray Crystallographic and CD Exciton Chirality Methods

1992 ◽  
Vol 57 (7) ◽  
pp. 1459-1465 ◽  
Author(s):  
Nobuyuki Harada ◽  
Tatsuo Sugioka ◽  
Hisashi Uda ◽  
Takeo Kuriki
Keyword(s):  
Structure Analysis ◽  
Absolute Configuration ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The 8aR absolute stereochemistry of Wieland-Miescher ketone (-)-I was established by the X-ray structure analysis of its bis(4-bromobenzoate) derivatives (1R,6R,8aR)-(+)-IV and (1R,6S,8aR)-(-)-V. The absolute configuration of (-)-I was corroborated further by the application of the CD exciton chirality method to bis(4-bromobenzoates) (+)-IV and (-)-V.

Determination of the Absolute Stereochemistry of Cyclosmenospongine

2003 ◽  
Vol 66 (9) ◽  
pp. 1263-1265 ◽  
Author(s):  
Natalia K. Utkina ◽  
Vladimir A. Denisenko ◽  
Olga V. Scholokova ◽  
Aleksandra E. Makarchenko
Keyword(s):  
The Absolute ◽  
Absolute Stereochemistry

Stereoselective deprotonation of tropinone and reactions of tropinone lithium enolate

1992 ◽  
Vol 70 (10) ◽  
pp. 2618-2626 ◽  
Author(s):  
Marek Majewski ◽  
Guo-Zhu Zheng
Keyword(s):  
Acetic Acid ◽  
Ring Opening ◽  
Aldol Reaction ◽  
Ethyl Chloroformate ◽  
Lithium Diisopropylamide ◽  
Silver Acetate ◽  
Lithium Amides ◽  
Lithium Enolate ◽  
The Absolute ◽  
Absolute Stereochemistry

Tropinone (6) was deprotonated with lithium diisopropylamide and with chiral lithium amides (18–24) and the resulting enolates (two enantiomers) were treated with electrophiles. The aldol reaction with benzaldehyde and deuteration were both diastereoselective. The former yielded only one isomer (exo, anti) of the aldol 8a; the latter proceeded from the exo face. This selectivity permitted us to probe the deprotonation of tropinone with lithium amides; it was concluded that the reaction involves predominantly the exo axial protons. The reaction of tropinone enolate with ethyl chloroformate led, via a ring opening, to the cycloheptenone derivative 9. The reaction with methyl cyanoformate yielded, in the presence of silver acetate and acetic acid, the β-ketoester 8b; however, in the absence of these additives, and especially when 12-crown-4 was added to the enolate, a ring opening leading to the pyrrolidine derivative 10 occurred instead. Deprotonation of tropinone with chiral lithium amides proceeded with modest enantioselectivity. A synthesis of non-racemic anhydroecgonine via this strategy allowed establishing the absolute stereochemistry of deprotonation.

First synthesis and determination of the absolute stereochemistry of iso-cladospolide-B and cladospolides-B and C

2006 ◽  
Vol 47 (37) ◽  
pp. 6537-6540 ◽  
Author(s):  
G.V.M. Sharma ◽  
K. Laxmi Reddy ◽  
J. Janardhan Reddy
Keyword(s):  
The Absolute ◽  
Absolute Stereochemistry

The absolute stereochemistry of the ester functions of fumonisin B1

1999 ◽  
Vol 40 (24) ◽  
pp. 4515-4518 ◽  
Author(s):  
Oliver E. Edward ◽  
Barbara A. Blackwell ◽  
Alex B. Driega ◽  
Corrine Bensimon ◽  
John W. ApSimon
Keyword(s):  
Fumonisin B1 ◽  
The Absolute ◽  
Absolute Stereochemistry
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