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Metal-catalyzed asymmetric synthesis of P-stereogenic phosphines.

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Call No.	QD181.P1 A54 2008
Author	Anderson, Brian Joseph.
Title	Metal-catalyzed asymmetric synthesis of P-stereogenic phosphines.
Date	2008
Abstract	Abstract (Summary) Chapter One. Platinum-Catalyzed Asymmetric Alkylation of Bis(secondary) Phosphines. Efficient Screening and the Synthesis of an Enantiomerically Pure C 2 -Symmetric Diphosphine. Platinum-catalyzed asymmetric alkylation of secondary phosphines is a useful method for synthesis of a variety of novel chiral phosphines and bisphosphines. We have developed efficient methodology for rapid screening of Pt catalyst precursors and benzyl halides in alkylation of bis(secondary) phosphines (RHP∼PHR). Enantiomerically pure P(Ph)( o -CF 3 CH 2 C 6 H 4 )(CH 2 ) 2 P(Ph)( o -CF 3 CH 2 C 6 H 4 ) was isolated. Chapter Two. Mechanistic Investigations of Pt-Catalyzed Asymmetric Alkylation of Bis(secondary) Phosphines. Catalyst Editing and Cooperativity. The Pt-catalyzed alkylation of 1,3-bis(phenylphosphino)propane ( 1 ) with benzyl bromide gave 1,3-bis(benzylphenylphosphino)propane ( 2 ) with an er of 68±12 and a dr of 4.2±0.3. The selectivity was controlled by the catalyst, as shown by the synthesis and alkylation of PhHP(CH 2 ) 3 P(Ph)(CH 2 Ph), which contained an enantiomerically enriched tertiary phosphine center. The major enantiomer was formed preferentially due to a catalyst editing process. A series of bis(secondary) phosphines PhHP(CH 2 ) n PHPh (n = 2-6) was examined in the Pt-catalyzed alkylation with benzyl bromide. The distereoselectivity and enantioselectivity of alkylation depended on n, being greatest for n = 3 or 4 and least for n = 2. Chapter Three. Enantioselective Synthesis of P-Stereogenic Benzophospholanes via Palladium-Catalyzed Intramolecular Cyclization. Enantioselective or diastereoselective intramolecular cyclization of functionalized secondary phosphines or their borane adducts catalyzed by chiral Pd(diphosphine) complexes gave P-stereogenic benzophospholanes in up to 70% ee. The chirality at phosphorus allowed for diastereoselective deprotonation/alkylation at the α-position. These results provide a new method for the synthesis of chiral phospholanes, which are valuable ligands in asymmetric catalysis. Chapter Four. Enantioselective Synthesis of P-Stereogenic 1- Phosphaacenaphthaenes via Pt-Catalyzed Intramolecular Cyclization of Secondary Phosphines and Pt-Catalyzed Alkylation/Cyclization of Primary and Bis(primary) Phosphines. Pt-catalyzed tandem alkylation/cyclization of primary phosphines with 1-bromo-8-chloromethylnaphthalene yielded novel 1-phosphaacenaphthenes in enantioenriched form. Similar reactions with bis(primary)phosphines formed potential chelate ligands with diastereo- and enantioselectivity. Enantioselective cyclization of the functionalized secondary phosphine 1-bromo-8-phenylphosphinomethylnaphthalene catalyzed by chiral Pt(DuPhos)(Ar)(Cl) complexes gave Ph-AcePhos in up to 72% ee. These reactions, which appear to proceed via an unusual metal-mediated nucleophilic aromatic substitution pathway, yield a new class of heterocycles with potential applications in asymmetric catalysis. Chapter Five. Synthesis, Structure, and Reactivity of Palladium Trans-stilbene Complexes, Catalyst Precursors with Novel Asymmetric Diphosphine Ligands. Novel catalyst precursors Pd(diphos)(trans-stilbene) ( 2a-c , diphos = PPF-t-Bu, CyPF-t-Bu, or BoPhoz) were prepared from the dichloride complexes Pd(diphos)Cl 2 ( 1a-c ). These catalyst precursors reacted more quickly with PhI to yield Pd(diphos)(Ph)(I) than the similar Pd(0) complexes Pd(diphos*)(dba). However, the stilbene complexes gave only racemic products in either inter- or intramolecular phosphination.
Description	xxv, 525 leaves : ill. (some col.) 28 cm.
Format	application/pdf
Advisor	Glueck, David S. Hughes, Russel P., BelBruno, Joseph, Waterman, Rory
Subject	Phosphine. Phosphorus compounds -- Synthesis. Platinum catalysts. Palladium catalysts. Asymmetric synthesis. Enantiomers.
College	Dartmouth College -- Department of Chemistry.
Issuing Body	Dartmouth Dissertations are made available through the Dartmouth Digital Library.
Degree	Thesis (Ph.D.)--Dartmouth College.
Copyright	All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means without permission in writing from the author.
DOI	http://dx.doi.org/10.1349/ddlp.230

Title	Page 1
Format	application/pdf
Issuing Body	Dartmouth Dissertations are made available through the Dartmouth Digital Library.
Degree	Thesis (Ph.D.)--Dartmouth College.
Full Text	Metal-Catalyzed Asymmetric Synthesis of P-Stereogenic Phosphines A Thesis Submitted to the Faculty in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry by Brian Joseph Anderson DARTMOUTH COLLEGE Hanover, New Hampshire June 9, 2008 Examining Committee: ____________________ (Chair) David S. Glueck ____________________ Russell P. Hughes ____________________ Joseph J. BelBruno ____________________ Rory Waterman __________________________ Charles K. Barlowe, Ph.D. Dean of Graduate Studies

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