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Ruthenium catalysis for atom economy...

Rudd, Michael Thomas.

Ruthenium catalysis for atom economy: Cycloisomerizations and hydrative cyclizations of alkynes.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Ruthenium catalysis for atom economy: Cycloisomerizations and hydrative cyclizations of alkynes.
Author:	Rudd, Michael Thomas.
Description:	637 p.
Notes:	Adviser: Barry M. Trost.
Notes:	Source: Dissertation Abstracts International, Volume: 65-11, Section: B, page: 5734.
Contained By:	Dissertation Abstracts International65-11B.
Subject:	Chemistry, Organic.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3153046
ISBN:	0496134922

Ruthenium catalysis for atom economy: Cycloisomerizations and hydrative cyclizations of alkynes.
Rudd, Michael Thomas.

Ruthenium catalysis for atom economy: Cycloisomerizations and hydrative cyclizations of alkynes. - 637 p.

Adviser: Barry M. Trost.

Thesis (Ph.D.)--Stanford University, 2005.

A novel and chemoselective ruthenium-catalyzed hydrative diyne cyclization is also described. Simple tethered internal alkynes are cyclized with the addition of a molecule of water to form five- and six-membered ring enones in high yields. The chemoselectivity of the process is demonstrated for a variety of unsymmetrical diynes. Generally, the presence of steric bulk adjacent to one of the alkynes in a diyne disfavors water addition at this alkyne. The power of this methodology to rapidly construct enones from readily available diynes is demonstrated in the synthesis of cylindricine C, D, and E.

ISBN: 0496134922Subjects--Topical Terms:

193634
Chemistry, Organic.

Ruthenium catalysis for atom economy: Cycloisomerizations and hydrative cyclizations of alkynes.
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100 0 $a Rudd, Michael Thomas. $3 237425
245 1 0 $a Ruthenium catalysis for atom economy: Cycloisomerizations and hydrative cyclizations of alkynes.
300 $a 637 p.
500 $a Adviser: Barry M. Trost.
500 $a Source: Dissertation Abstracts International, Volume: 65-11, Section: B, page: 5734.
502 $a Thesis (Ph.D.)--Stanford University, 2005.
520 # $a A novel and chemoselective ruthenium-catalyzed hydrative diyne cyclization is also described. Simple tethered internal alkynes are cyclized with the addition of a molecule of water to form five- and six-membered ring enones in high yields. The chemoselectivity of the process is demonstrated for a variety of unsymmetrical diynes. Generally, the presence of steric bulk adjacent to one of the alkynes in a diyne disfavors water addition at this alkyne. The power of this methodology to rapidly construct enones from readily available diynes is demonstrated in the synthesis of cylindricine C, D, and E.
520 # $a A ruthenium-catalyzed cross-coupling of propargylic alcohols and simple alkynes can also be carried out to form alpha,beta,gamma,delta-unsaturated ketones. The intermolecular process is somewhat limited at the present time, but the corresponding intramolecular cycloisomerization is quite efficient for the construction of a variety of dienones and dienals. Five- and six-membered rings are formed utilizing diynols with tertiary, secondary or primary propargylic alcohols. The efficiency and utility of the primary propargylic alcohol diyne cycloisomerization is demonstrated in the synthesis of the unnatural enantiomer of alpha-kainic acid.
520 # $a Tertiary, terminal propargylic alcohols readily undergo a highly novel dimerization process in the presence of [CpRu(CH3CH) 3]PF6 to produce unsaturated ketones and aldehydes in a stereoselective fashion. The reaction conditions can be varied to favor the formation of alpha,beta,gamma,delta-unsaturated-alpha '-hydroxy-ketones, and the scope of this transformation is demonstrated for a variety of propargylic alcohols.
520 # $a The use of silyl-diynols in the ruthenium-catalyzed cycloisomerization is demonstrated as well. Instead of the expected acylsilanes, however, 2-silyl-[6H]-pyrans or silyl-dihydropyrans are isolated. The amount of water in the solvent can be used to control the regioselectivity of the process, forming either 2-silyl-[6H]-pyrans or silyl-dihydropyrans. Substrates which contain a heteroatom in the tether have a reduced tendency to isomerize to silyl-dihydropyrans. It is demonstrated through DFT calculations that the electrocyclization of alpha,beta,gamma,delta-unsaturated acylsilanes to 2-silyl-[6H]-pyrans is favored by 13 kcal/mol. Studies towards the synthesis of epoxyquinol A and B were carried out using this methodology.
590 $a School code: 0212.
650 # 0 $a Chemistry, Organic. $3 193634
690 $a 0490
710 0 # $a Stanford University. $3 212607
773 0 # $g 65-11B. $t Dissertation Abstracts International
790 $a 0212
790 1 0 $a Trost, Barry M., $e advisor
791 $a Ph.D.
792 $a 2005
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