Synthesis and kinetic studies of tricyclic phosphates and phosphonates: Effect of phosphorus-oxide stereochemistry on allylic rearrangements

"The role of allylic pyrophosphates in terpene biosynthesis is thought to involve S$\sb{\rm N}$1-type ionization leading to an ion-pair. In this work, kinetic studies are reported on tricyclic phosphates and phosphonates which were prepared from 11 and 12 step syntheses. First order rate constants for solvolysis (k$\sb{\rm s}$) and loss of optical activity (k\sbα) were measured for 12a and 12b under solvolytic conditions (30% D$\sb2$O/70% acetone-d$\sb6$, 25$\sp\circ$C). For phosphate 12a, k\sbα/k$\sb{\rm s}$ = 1.7 while for 12b, k\sbα/k$\sb{\rm s}$ = 1. Phosphates 12a and 12b cleanly interconvert when heated in nitrobenzene at 145$\sp\circ$C. Rate constants for isomerization (k$\sb{\rm i}$) and loss of optical activity (k\sbα) were measured, and for 12a k\sbα/k$\sb{\rm i}$ = 295 while for 12b k\sbα/k$\sb{\rm i}$ = 2.4. The rate ratios of each phosphate isomer are clearly influenced by the stereochemistry of the P-oxide group. A mechanism for solvolysis and interconversion involving symmetrical and unsymmetrical ""bidentate"" ion-pairs is discussed.(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI)"

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Rotto, Nelson Torr

Contributors dc:contributor

• Coates, Robert M.

• Chemistry, Organic

Statement dc:rights

• Copyright 1989 Rotto, Nelson Torr

Language dc:language

eng

Identifier

AAI9011003
(UMI)AAI9011003

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/19805