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Synthesis of hongconin and related naphtho[2,3-c]pyrans
Author(s)
Oosthuizen, Francois Jacobus
Date Issued
1995
Type
Thesis
Publisher
Cape Technikon
Abstract
The naphtho[2,3-c]pyran occurs frequently in nature as derivatives of the 5,10 quinones.
The most common examples include the eleutherins and protoaphins.
These naturally occurring compounds have been found to possess antibiotic activity
through the process of bioactivation. The possibility of appropriately substituted
compounds functioning as bioreductive alkylating agents provides a logical model
that has a great deal of predictive power.
The thesis deals with the synthesis of some naphtho[2,3-c]pyrans to be tested
biologically; the challenge being to design compounds in a biologically inactive form
which become activated only subsequent to an in-vivo transformation.
Chapter One describes and compares a high yielding synthesis of a naphtho[2,3c]
pyran, hongconin, to a previous route.,a Racemic hongconin (29) has been
synthesised from adduct (43) formed by reaction between 1-methoxycyclohexa1,4-
diene (41) and 1,4-benzoquinone (42). The key steps
includes Fries and Claisen rearrangements, base and cerium(lVj initiated pyran ring
formation, C-4 pyran ring hydroxylation and silver(ll) mediated oxidation. The
target compound (29) was tested in vitro for antimicrobial activity and compared
to the results obtained for isoeleutherin (2) and its 9-demethoxy analoque (30).
The spectral data, melting points and yields of the individual compounds is as
described in Chapter Two.
The most common examples include the eleutherins and protoaphins.
These naturally occurring compounds have been found to possess antibiotic activity
through the process of bioactivation. The possibility of appropriately substituted
compounds functioning as bioreductive alkylating agents provides a logical model
that has a great deal of predictive power.
The thesis deals with the synthesis of some naphtho[2,3-c]pyrans to be tested
biologically; the challenge being to design compounds in a biologically inactive form
which become activated only subsequent to an in-vivo transformation.
Chapter One describes and compares a high yielding synthesis of a naphtho[2,3c]
pyran, hongconin, to a previous route.,a Racemic hongconin (29) has been
synthesised from adduct (43) formed by reaction between 1-methoxycyclohexa1,4-
diene (41) and 1,4-benzoquinone (42). The key steps
includes Fries and Claisen rearrangements, base and cerium(lVj initiated pyran ring
formation, C-4 pyran ring hydroxylation and silver(ll) mediated oxidation. The
target compound (29) was tested in vitro for antimicrobial activity and compared
to the results obtained for isoeleutherin (2) and its 9-demethoxy analoque (30).
The spectral data, melting points and yields of the individual compounds is as
described in Chapter Two.
Additional information
Thesis (MTech (Chemistry))--Cape Technikon, Cape Town,1995
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