Synthesis of carbocycles from ω-substituted α,β-unsaturated esters via radical-induced cyclizations

1987 ◽  
Vol 65 (8) ◽  
pp. 1859-1866 ◽  
Author(s):  
Stephen Hanessian ◽  
Daljit S. Dhanoa ◽  
Pierre L. Beaulieu
Keyword(s):  
Ester Group ◽  
Carbon Chain ◽  
Radical Cyclization ◽  
Unsaturated Esters ◽  
Carbocyclic Compounds ◽  
Bicyclic Structure

The intramolecular radical cyclization of ω-bromo α,β-unsaturated esters for the synthesis of carbocyclic compounds is described. The effect of carbon chain substituents, the bulk of the ester group, and the olefin geometry were examined. The highest level of stereoselectivity (trans/cis: 9/1) was achieved with the Z ester via an exo cyclization. The sequential radical cyclization of a dihalodienoate to give a cis-fused bicyclic structure is also described.

Cocaine: Pharmacokinetics and biotransformation in man

1989 ◽  
Vol 67 (9) ◽  
pp. 1154-1157 ◽  
Author(s):  
T. Inaba
Keyword(s):  
Methyl Ester ◽  
Ester Group ◽  
Oral Route ◽  
Plasma Cholinesterase ◽  
Pharmacokinetic Studies ◽  
Hydrolytic Cleavage ◽  
Bicyclic Structure ◽  
Anesthetic Action ◽  
Pharmacologically Active ◽  
Cytochrome P 450

Pharmacokinetic studies of cocaine have been carried out only in the last decade, although its local anesthetic action and addictive properties have been known for almost 100 years. Elimination half-lives of cocaine in man estimated from serial plasma concentration are relatively short and range from 0.5 to 1.1 h after i.v. and 0.9–1.5 h after administration by the nasal or oral route. The bioavailability after nasal inhalation is about 60%. The bicyclic structure of cocaine is characterized by functional groups including N-methyl, carboxyl methyl ester, and benzoyl ester, which are susceptible to biotransformation. Hydrolysis of the benzoyl group to ecgonine methyl ester is catalyzed by plasma cholinesterase and is thus under monogenic control. The hydrolytic cleavage of the other ester group, methyl ester, to benzoyl ecgonine occurs spontaneously at body temperature. In contrast, N-demethylation of cocaine mediated by microsomal cytochrome P-450 produces norcocaine and this metabolite was shown to be pharmacologically active, the action being similar to cocaine.Key words: cocaine, hydrolysis, plasma cholinesterase, cytochrome P-450.

Evaluation of Biodegradability of Amine Collectors

2010 ◽  
Vol 113-116 ◽  
pp. 267-271 ◽  
Author(s):  
Heng Zhen Yan ◽  
Wen Qi Gong ◽  
Guang Jun Mei ◽  
Xiao Ye Liu ◽  
Shao Hua Chen
Keyword(s):  
Chemical Structure ◽  
Ester Group ◽  
Carbon Chain ◽  
Ammonium Bromide ◽  
Evaluation Standards ◽  
Testing Method

Amine collectors are widely used as oxidized ore collectors.Based on OECD 301B testing method, the biodegradability of amine collectors were analyzed and evaluated, and the values of IB of lauryl amine, octadecylamine, laurtrimonium chloride, lauryl trimethyl ammonium bromide, decane-propyl ether amine and dodecyl propyl ether amine were 173.4, 162.2, 164.6, 171.2, 160.8 and 149.4, respectively. The biodegradation of six test substances all exceeded 10% in 10 days, and all up to over 50% within 28 days. Considering comprehensively the two evaluation standards, the six amine collectors are all biodegradable. Evaluation of the biodegradability of amine collectors provides information that the chemical structure influences the biodegradability of amine collectors. It seems that the existence of ester group decreases the biodegradability of ether amine, and the shorter the carbon chain, the greater the biodegradation occurred.

Lewis Acid-Promoted Diastereoselective Radical Cyclization Using Chiral .alpha.,.beta.-Unsaturated Esters

1994 ◽  
Vol 116 (14) ◽  
pp. 6455-6456 ◽  
Author(s):  
Mayumi Nishida ◽  
Eiji Ueyama ◽  
Hiroshi Hayashi ◽  
Yoshihito Ohtake ◽  
Yousuke Yamaura ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Radical Cyclization ◽  
Unsaturated Esters ◽  
Alpha Beta

Lengthening of the Alkyl Chain in Steroid O-(ω-Carboxyalkyl)oximes by Wittig Reaction

1998 ◽  
Vol 63 (10) ◽  
pp. 1623-1634 ◽  
Author(s):  
Vladimír Pouzar ◽  
Tereza Slavíková ◽  
Ivan Černý
Keyword(s):  
Wittig Reaction ◽  
Alkyl Chain ◽  
Carbon Chain ◽  
Hydroxyl Groups ◽  
Unsaturated Esters ◽  
Alkyl Length

The steroid O-alkyloximes with various alkyl length (2-4 carbons) and with terminal hydroxyl groups were oxidized to aldehydes and their Wittig reaction with triethyl phosphonoacetate was studied. Oximes derived from 17-oxoandrost-5-en-3β-yl acetate and from 7-oxo and 19-oxocholest-5-en-3β-yl acetate were used. Except of 7- and 19-[O-(2-hydroxyethyl)]oximes, all the hydroxyalkyloximes gave successively aldehydes and corresponding unsaturated esters. The method is useful for the lengthening of the carbon chain in ω-substituted O-alkyloximes.

Intramolecular [2 + 2]photocycloadditions of 1-(.omega.-alkenyl)-2-pyridones possessing an ester group on the olefinic carbon chain

1992 ◽  
Vol 57 (21) ◽  
pp. 5708-5712 ◽  
Author(s):  
Kenichi Somekawa ◽  
Hiroyuki Okuhira ◽  
Masayuki Sendayama ◽  
Takaaki Suishu ◽  
Tetsuro Shimo
Keyword(s):  
Ester Group ◽  
Carbon Chain ◽  
Olefinic Carbon

Multiple Carbon Bond Formation Via the Radical Cyclization of Cycloalkenol Acetals. Application to trans Hydrindan Steroid Precursors

1992 ◽  
Vol 45 (1) ◽  
pp. 275 ◽  
Author(s):  
G Stork ◽  
PJ Franklin
Keyword(s):  
Double Bond ◽  
Bond Formation ◽  
Carbon Chain ◽  
Radical Cyclization ◽  
Carbon Bond ◽  
Single Operation ◽  
Carbon Carbon Bonds ◽  
Carbon Bonds

The cyclization of the α-iodo mixed acetals derived from properly substituted cyclohexenols , a process which has already been shown to permit the stereoselective and regioselective introduction of a different carbon chain at each of the termini of the allylic double bond, may be used for the construction of trans hydrindans suitable for further elaboration to steroids. In one particular instance, the process involves the formation of four new carbon-carbon bonds in a single operation.

ChemInform Abstract: Intramolecular (2 + 2)Photocycloadditions of 1-(ω-Alkenyl)-2- pyridones Possessing an Ester Group on the Olefinic Carbon Chain.

ChemInform ◽  
2010 ◽  
Vol 24 (7) ◽  
pp. no-no
Author(s):  
K. SOMEKAWA ◽  
H. OKUHIRA ◽  
M. SENDAYAMA ◽  
T. SUISHU ◽  
T. SHIMO
Keyword(s):  
Ester Group ◽  
Carbon Chain ◽  
Olefinic Carbon
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