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Molybdenum-catalyzed asymmetric allylic alkylation reactions :Methodology and applications

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Molybdenum-catalyzed asymmetric allylic alkylation reactions :
其他題名:	Methodology and applications
作者:	Dogra, Kalindi.
面頁冊數:	308 p.
附註:	Adviser: Barry M. Trost.
附註:	Source: Dissertation Abstracts International, Volume: 65-04, Section: B, page: 1865.
Contained By:	Dissertation Abstracts International65-04B.
標題:	Chemistry, Organic.
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3128643
ISBN:	0496759051

Molybdenum-catalyzed asymmetric allylic alkylation reactions :Methodology and applications
Dogra, Kalindi.

Molybdenum-catalyzed asymmetric allylic alkylation reactions :Methodology and applications [electronic resource] - 308 p.

Adviser: Barry M. Trost.

Thesis (Ph.D.)--Stanford University, 2004.

Aryl allyl, conjugated alkene, alkyne-alkene and simple aliphatic allylic species function as electrophilic partners in this reaction. Carbonates are the preferred leaving group, though phosphates are also utilized when a better leaving group is required.

ISBN: 0496759051Subjects--Topical Terms:

193634
Chemistry, Organic.

Molybdenum-catalyzed asymmetric allylic alkylation reactions :Methodology and applications
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520 # $a Aryl allyl, conjugated alkene, alkyne-alkene and simple aliphatic allylic species function as electrophilic partners in this reaction. Carbonates are the preferred leaving group, though phosphates are also utilized when a better leaving group is required.
520 # $a The Molybdenum-catalyzed asymmetric allylic alkylation (Mo-AAA) reaction was developed. A better understanding of the catalyst structure and reaction mechanism have been gained with the help of rational ligand design. It has been discovered that the ligand binds in a tridentate fashion through the pyridine and amide nitrogens of one picolinamide group and through the carbonyl oxygen of the other amide moiety. During the course of the reaction this carbonyl group is replaced with the nucleophile, which attacks the pi-allyl internally to form the product.
520 # $a The synthesis of baclofen sets the stereocenter by the Mo-AAA of p-chlorophenyl allyl carbonate with dimethyl malonate. Carbodemethoxylation under Krapcho conditions, followed by ozonolysis under reducing conditions yields the known 3-(p-chlorophenyl)-butyrolactone, which is converted to baclofen. Mo-AAA of 4,6-dimethoxy-2-(4-methoxyphenyl) benzofuran-3(2 H)-one with cinnamyl carbonate, followed by hydroboration and oxidation yields the targeted intermediate in the synthesis of rocaglamide.
520 # $a The synthetic utility of the reaction has been demonstrated by its use in the synthesis of Delta9-THC, baclofen and an intermediate in the synthesis of rocaglamide. All of the stereochemistry in synthesis of Delta 9-THC results from a single Mo-AAA reaction of methyl 3-(2,6-dimethoxy-4-phenyl-phenyl)-allyl carbonate with dimethyl malonate. Conversion of the malonate to the corresponding mono-acid, followed by alkylation of the acid and ring-closing metathesis results in a fixed position of the double bond, solving the problem of co-formation of Delta8-THC that is seen in many syntheses. Grignard addition to the ring-closed ester results in the 3° alcohol followed by deprotection to the free phenol and subsequent cyclization to give the core. Deprotection of the second phenol leads to Delta9-THC.
520 # $a beta-Keto esters, beta-cyano esters, malonates and substituted malonates function well as nucleophiles in the reaction, but highly stabilized enolates do not. Non-stabilized enolates of aromatic acetates and ketones react extremely fast under the reaction conditions. The selectivity of the reaction for aromatic acetates can be improved by using a catalytic amount of base with stoichiometric amounts of BSA. This also allows for a lowering of the catalyst loading. Azlactone nucleophiles gave quaternary amido esters in very high regio-, diastereo- and enantioselectivity. Oxalactims were discovered as a new class of nucleophiles for the synthesis of alpha-hydroxy amides.
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