REGIOSELECTIVITY IN THE PHOTOCYCLIZATION OF STILBENES
REGIOSELECTIVITY IN THE PHOTOCYCLIZATION OF STILBENES
批准号:
3438400
负责人:
FRANK B MALLORY
金额:
$7.81万
依托单位:
依托单位国家:
美国
项目类别:
财政年份:
1985
资助国家:
美国
项目状态:
已结题
起止时间:
1985-11-01 至 1988-10-31
中文摘要
这一建议的目的是开发的综合潜力
英文摘要
The objective of this proposal is to develop the synthetic potential of the
photocyclization reaction in which the ultraviolet irradiation of
o-methoxystilbenes in the absence of dissolved oxygen gives 4a-methoxy-4a,
4b-dihydrophenanthrenes as transient intermediates that subsequently can
undergo elimination of methanol to give phenanthrenes. Except for a few
examples of this eliminative photocyclization that were reported by other
workers in 1974, this reaction has remained largely overlooked. Studies
will be carried out with the parent o-methoxystilbene to establish optimum
reaction conditions; in particular, the hypothesis will be tested that this
eliminative photocyclization will proceed better in acidified methanol than
it has in cyclohexane. Studies will be undertaken of the viability of this
reaction as a method to overcome the regiochemical problems that sometimes
limit the synthetic value of the well-known oxidative photocyclization
method. For example, oxidative photocyclizations of meta-substituted
stilbenes give mixtures of 2- and 4-substituted phenanthrenes, often with
almost no regioselectivity. The eliminative photocyclizations of
2-methoxy-5-methylstilbene and 2-methoxy-3-methylstilbene will be carried
out to test the hypothesis that these reactions will produce individual
samples of 2- and 4-methylphenanthrene, respectively.
Oxidative photocyclizations of 2-styrylnaphthalenes exhibit high
regioselectivity, giving almost exclusively benzo[c]phenanthrenes; the
regioisomeric benz[a]anthracenes are formed only in trace amounts. For
similar reasons, the dibenz[a,j]anthracene and dibenz[a,h]anthracene
systems also are not available by oxidative photocyclization. It is
proposed to try to provide synthetic access to the benz[a]anthracene,
dibenz[a,j]-anthracene, and dibenz[a,h]anthracene systems by carrying out
eliminative photocyclizations of 3-methoxy-2-styrylnaphthalene,
2,4-dimethoxy-1,5-distyrylbenzene, and 2,5-dimethoxy-1,4-distyrylbenzene,
respectively.
These proposed experimental attempts to develop the synthetic utility of
the eliminative photocyclization method focus on the simplest molecular
examples, but the ultimate aim is to consider these examples as prototypes
for future applications of the method to multi-substituted systems. The
expansion of the capabilities for synthesizing polynuclear aromatic systems
of the type considered here should have future importance for
health-related studies because of the widespread occurrence of
physiologically active natural products related to phenanthrenes, and the
carcinogenicity of benzanthracenes.
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NANOSCALE POLYCYCLIC AROMATIC HYDROCARBON DERIVATIVES
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批准号:2605400
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项目类别:
-
资助金额:$10.33万
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财政年份:1998
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负责人:FRANK B MALLORY
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依托单位:
海外基金