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Development of enantioselective meth...

Duke University.

Development of enantioselective methodology for, and mechanistic investigation of palladium-catalyzed cyclization/hydrosilylation of functionalized dienes.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Development of enantioselective methodology for, and mechanistic investigation of palladium-catalyzed cyclization/hydrosilylation of functionalized dienes.
Author:	Perch, Nicholas Stafford.
Description:	133 p.
Notes:	Source: Dissertation Abstracts International, Volume: 65-06, Section: B, page: 2939.
Notes:	Supervisor: Ross A. Widenhoefer.
Contained By:	Dissertation Abstracts International65-06B.
Subject:	Chemistry, Organic.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3135139
ISBN:	0496823639

Development of enantioselective methodology for, and mechanistic investigation of palladium-catalyzed cyclization/hydrosilylation of functionalized dienes.
Perch, Nicholas Stafford.

Development of enantioselective methodology for, and mechanistic investigation of palladium-catalyzed cyclization/hydrosilylation of functionalized dienes. - 133 p.

Source: Dissertation Abstracts International, Volume: 65-06, Section: B, page: 2939.

Thesis (Ph.D.)--Duke University, 2003.

Cyclization/hydrosilylation of 5 with HSiEt3 catalyzed by [(phen)Pd(Me)(NCAr)]+ [BAr4] - (57) is initiated by reaction of 57 with HSiEt3 to produce [(phen)Pd(SiEt3)(NCAr)] + [BAr4]- (72). Complex 72 reacts with 5 at -62°C to form {(phen)Pd[eta 1:eta2-CH(CH2SiEt3)CH 2C(CO2Me)2CH2CH=CH2]} + [BAr4]- (73) in 84% yield (t1/2 = 5 min). Warming a solution of 73 and NCAr at -41°C for 2 hours leads to formation of {(phen)Pd[CH 2CHCH2C(CO2Me)2CH2CHCH 2SiEt3](NCAr)}+ [BAr4]- (74) in 96% yield. Conversion of 73 to 74 represents the first direct observation of intramolecular beta-migratory insertion of an alkyl-olefin chelate complex. 74 reacts in <10 min. with HSiEt3 at -41°C to release 6 and regenerate 72. The activation parameters for 5 + HSiEt3 → 6 (DeltaG &Dagger; = 16.9 +/- 0.1 kcal mol-, Delta H&Dagger; = 13 +/- 1 kcal mol- and DeltaS&Dagger; = -15 +/- 3 eu) match those determined for 73 → 74 (Delta G&Dagger; = 16.9 +/- 0.1 kcal mol- , DeltaH&Dagger; = 13.5 +/- 0.6 kcal mol- and DeltaS&Dagger; = -15 +/- 2 eu), and differ significantly from reported activation parameters for insertion of non-chelated alkyl-olefin complexes.

ISBN: 0496823639Subjects--Topical Terms:

193634
Chemistry, Organic.

Development of enantioselective methodology for, and mechanistic investigation of palladium-catalyzed cyclization/hydrosilylation of functionalized dienes.
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100 0 $a Perch, Nicholas Stafford. $3 227920
245 1 0 $a Development of enantioselective methodology for, and mechanistic investigation of palladium-catalyzed cyclization/hydrosilylation of functionalized dienes.
300 $a 133 p.
500 $a Source: Dissertation Abstracts International, Volume: 65-06, Section: B, page: 2939.
500 $a Supervisor: Ross A. Widenhoefer.
502 $a Thesis (Ph.D.)--Duke University, 2003.
520 # $a Cyclization/hydrosilylation of 5 with HSiEt3 catalyzed by [(phen)Pd(Me)(NCAr)]+ [BAr4] - (57) is initiated by reaction of 57 with HSiEt3 to produce [(phen)Pd(SiEt3)(NCAr)] + [BAr4]- (72). Complex 72 reacts with 5 at -62°C to form {(phen)Pd[eta 1:eta2-CH(CH2SiEt3)CH 2C(CO2Me)2CH2CH=CH2]} + [BAr4]- (73) in 84% yield (t1/2 = 5 min). Warming a solution of 73 and NCAr at -41°C for 2 hours leads to formation of {(phen)Pd[CH 2CHCH2C(CO2Me)2CH2CHCH 2SiEt3](NCAr)}+ [BAr4]- (74) in 96% yield. Conversion of 73 to 74 represents the first direct observation of intramolecular beta-migratory insertion of an alkyl-olefin chelate complex. 74 reacts in <10 min. with HSiEt3 at -41°C to release 6 and regenerate 72. The activation parameters for 5 + HSiEt3 → 6 (DeltaG &Dagger; = 16.9 +/- 0.1 kcal mol-, Delta H&Dagger; = 13 +/- 1 kcal mol- and DeltaS&Dagger; = -15 +/- 3 eu) match those determined for 73 → 74 (Delta G&Dagger; = 16.9 +/- 0.1 kcal mol- , DeltaH&Dagger; = 13.5 +/- 0.6 kcal mol- and DeltaS&Dagger; = -15 +/- 2 eu), and differ significantly from reported activation parameters for insertion of non-chelated alkyl-olefin complexes.
520 # $a Enantioselective cyclization/hydrosilylation of dimethyl diallylmalonate (5) with HSiEt3 catalyzed by {[(S, S)-4,4'-dibenzyl-2,2'-bis(2-oxazoline)] Pd(Me)Cl} and NaBAr4 [Ar = 3,5-C6H3(CF 3)2] (1:1) in CH2Cl2 at 25°C gave a 5:1 mixture of S,S-1,1-dicarbomethoxy-4-methyl-3-(triethylsilyl)methylcyclopentane (6) (54% ee) and dimethyl 3,4-dimethylcyclopentane-1,1-dicarboxylate (7) (35% ee) (70% combined). Formation of 7 was traced to the presence of water in the reaction mixture. Pyridine-oxazoline complexes were in general superior catalysts to bisoxazoline complexes. Reaction of 5 and HSiEt3 catalyzed by [(4-i-propyl-2-(2-pyridyl)-2-oxazoline)Pd(Me)Cl] (10) and NaBAr4 at -32°C gave 6 in 82% yield (>95% de, 84% ee).
590 $a School code: 0066.
650 # 0 $a Chemistry, Organic. $3 193634
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710 0 # $a Duke University. $3 226880
773 0 # $g 65-06B. $t Dissertation Abstracts International
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790 1 0 $a Widenhoefer, Ross A., $e advisor
791 $a Ph.D.
792 $a 2003
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