Cation-exchange resins: Efficient heterogeneous catalysts for facile synthesis of dibenzoxanthene from β-naphthol and aldehydes

Article abstract of DOI:10.1080/00397910600639372

β-Naphthol reacts with alkyl and aryl aldehydes in the presence of Indion-130 to give 14-alkyl/aryl-14H[ a,j ]dibenzoxanthenes in good yield. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910600639372

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Cation‐Exchange Resins: Efficient
Heterogeneous Catalysts for Facile Synthesis
of Dibenzoxanthene from β‐Naphthol and
Aldehydes
Sachin B. Patil a , Ramakrishna P. Bhat a & Prof. Shriniwas D. Samant a
a Organic Chemistry Research Laboratory, University Institute of Chemical
Technology, Matunga, Mumbai, India
Published online: 16 Feb 2007.
To cite this article: Sachin B. Patil , Ramakrishna P. Bhat & Prof. Shriniwas D. Samant (2006) Cation‐Exchange
Resins: Efficient Heterogeneous Catalysts for Facile Synthesis of Dibenzoxanthene from β‐Naphthol and
Aldehydes, Synthetic Communications: An International Journal for Rapid Communication of Synthetic
Organic Chemistry, 36:15, 2163-2168, DOI: 10.1080/00397910600639372
To link to this article: http://dx.doi.org/10.1080/00397910600639372
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Synthetic Communicationsw, 36: 2163–2168, 2006
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910600639372
Cation-Exchange Resins: Efficient
Heterogeneous Catalysts for Facile
Synthesis of Dibenzoxanthene from
b-Naphthol and Aldehydes
Sachin B. Patil, Ramakrishna P. Bhat,
and Shriniwas D. Samant
Organic Chemistry Research Laboratory, University Institute of Chemical
Technology, Matunga, Mumbai, India
Abstract: b-Naphthol reacts with alkyl and aryl aldehydes in the presence of
Indion-130 to give 14-alkyl/aryl-14H[a,j]dibenzoxanthenes in good yield.
Keywords: Cation exchange resins, dibenzoxanthenes, Indion-130
INTRODUCTION
Despite their wide range of biological,[1] pharmaceutical,[2] and synthetic
applications,[3] the synthesis of dibenzoxanthenes have received of little
attention. The synthesis may be achieved by cycloacylation of carbamates,[4]
trapping of benzynes by phenol,[5] cyclocondensation of 2-hydroxyaromatic
aldehyde with 2-tetralone,[6] and intramolecular phenyl carbonyl coupling
reaction of benzaldehyde and acetophenone.[7] Other methods involve
reaction of b-naphthol with aldehydes,[8] aldehyde acetal,[9] formamide,[10]
carbon monoxide,[11] and 2-naphthol-1-methanol.[12] The reaction of
b-naphthol with aldehydes can be catalyzed by a Brønsted acid such as
H2SO4,[8a] HCl,[8b] or p-TSA.[8c] Theses conventional catalysts are often
Received Jaunary 3, 2006
Address correspondence to Prof. Shriniwas D. Samant, Applied Chemistry Division,
Organic Chemistry Research Laboratory, University Institute of Chemical Technology,
N. M. Parekh Marg, Matunga, Mumbai 400 019, India. Tel: þ91-022-24145616;
Fax: þ91-022-24145614; E-mail: samantsd@udct.org, samantsd@yahoo.com
2163

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2164
S. B. Patil, R. P. Bhat, and S. D. Samant
toxic, corrosive, and difficult to separate and recover from the products,
despite their higher catalytic activity. There are no reports on the use of het-
erogeneous solid acids such as clays, zeolites, and ion-exchange resins for the
synthesis of dibenzoxanthenes.
In this communication, we report for the first time a facile and efficient
synthetic strategy for preparing 14-alkyl/aryl-14H[a,j]dibenzoxanthenes in
excellent yield using cation-exchange resins as heterogeneous catalysts
(Scheme 1).
RESULTS AND DISCUSSION
Different heterogeneous acidic catalysts were used for condensation of
b-naphthol with 4-chlorobenzaldehyde (Scheme 1). All the catalysts were
of analytical grade procured from firms of repute: Amberlyst 15 and
Mont. K-10 were obtained from Fluka (USA); Amberlyst 36 from Rohm
and Hass (USA); Indion-130 and Indion- 140 from Ion Exchanged India
Ltd. (India); and silica from S. D. Fine Chem Ltd. (India). Among these,
Indion-130, Indion-140, and Amberlyst-15 were found to be efficient and
gave 86–94% yield of the product in 12–18 min. Amberlyst-36 and silica
were not very effective and gave 38 and 28% yield of the product in
45 min and 120 min, respectively. K-10 was totally ineffective for the
transformation.
Various aldehydes were reacted with b-naphthol in the presence of
Indion-130 to obtain 14-alkyl/aryl-14H[a,j]dibenzoxanthenes under these
reaction conditions (Table 1). The nature of the substituent on the aromatic
ring had a profound effect on the yield of the product. The electron-
donating group needed a longer reaction time to give satisfactory yield than
the electron-withdrawing group present on aldehyde. For example, 4-chloro-
benzaldehyde reacted rapidly with b-naphthol to give the product in
excellent yield within 12 min, whereas aliphatic aldehydes (propanal and
isobutyraldehyde) needed 50–60 min for comparable yields.
The reusability of the catalyst was checked by separation, drying, and
reloading the same catalyst for the new run. We found that the catalyst
could be reused several times. For example, the yield of 3c was 89%, 86%,
and 81% in three successive runs.
Scheme 1.

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Cation-Exchange Resins
2165
Table 1. Condensation reactions between b-naphthol and aldehydes in the presence
of Indion-130a
Yield
(%)b
Time
(min)
Entry
Aldehyde 1
Product 3
M.p (8C) [lit.]
184–185
[185[9]
1
91
88
94
92
90
20
12
12
18
20
]
213–214
[215[8c]
2
3
4
5
]
289–290
[289[8c]
]
296–297
[297[9]
]
192–193
[192[8c]
]
(continued)