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Studies directed toward the synthesis of palau'amine and axinellamines A-D

Citation

Starr, Jeremy Tyson (2001) Studies directed toward the synthesis of palau'amine and axinellamines A-D. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/114f-cx28. https://resolver.caltech.edu/CaltechTHESIS:03212014-142648295

Abstract

The use of spiro [2.4]hepta-4,6-diene-1-methanol 7 as a general precursor for the synthesis of highly functionalized cyclopentyl rings is described. Diene 7 was converted to its silyl protected 4-nitrile derivative 24 in 46% overall yield. The cyclopropyl ring of 24 reacted with soft carbanionic nucleophiles to give ring opened homo-conjugate addition products 25a-h in 76-97% yield without loss of optical purity. The addition products could be further manipulated by selective mono-hydrogenation to give 1,2 substituted cyclopentenes 26a-e in 85-96% yield.

Diene 7 was used as a starting material for studies directed toward the synthesis of the stereochemically dense chloro-cyclopentyl core of palau'amine 1. Two advanced intermediates 50 and 72 were synthesized. Attempts to effect intramolecular chlorine transfer with 50 were unsuccessful. Attempted intramolecular chlorine transfer with 72 led, instead, to an oxygenated species resulting from oxygen radical trapping.

The enantioselective synthesis of the stereochemically dense chloro-cyclopenty l core of axinellamines A-D 2-5 starting from 7 is also described. The core is synthesized in 4.6% yield over 24 steps. Nakamura's radical dehalogenative hydroxylation is applied for the first time to a cyclopropyl carbonyl iodide to give the ring-opened product in 86% yield. Bolm's meso-anhydride desymmetrization is used to introduce asymmetry in a norbornene intermediate. The final step is a diastereoselective intermolecular chlorination using Barton's methodology to achieve chlorine transfer in 76% yield.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemistry
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Carreira, Erick Moran
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 September 2000
Record Number:CaltechTHESIS:03212014-142648295
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:03212014-142648295
DOI:10.7907/114f-cx28
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8159
Collection:CaltechTHESIS
Deposited By: John Wade
Deposited On:21 Mar 2014 22:00
Last Modified:16 Apr 2021 22:27

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