Journal of Fluorine Chemistry
Hexafluoroisopropanol dispersed into the nanoporous SBA-15 (HFIP/
SBA-15) as a rapid, metal-free, highly reusable and suitable combined
catalyst for domino cyclization process in chemoselective preparation
of alkyl rhodanines
1
1
*
Sadegh Rostamnia , Esmail Doustkhah , Ayat Nuri
Organic and Nano Group (ONG), Department of Chemistry, Faculty of Science, University of Maragheh, P.O. Box 55181-83111, Maragheh, Iran
A R T I C L E I N F O
A B S T R A C T
Article history:
Hexafluoroisopropanol dispersed catalytically amount of SBA-15 (HFIP/SBA-15) with organic substrate
was found to be an efficient, ultra-fast and waste-free approach for the synthesis of the biologically and
pharmaceutically interesting alkyl rhodanines. The advantages of the present method are low catalyst
loading, simple procedure, waste-free and direct synthetic entry to excellent yield of rhodanines, high
reusability of the catalyst, and short reaction time. Also, the reaction can be performed without
activation and modification of the substrates under the neutral conditions. The solid SBA-15 and HFIP
could be recovered and reused for recycling.
Received 7 April 2013
Received in revised form 23 May 2013
Accepted 27 May 2013
Available online 18 June 2013
Keywords:
Fluorinated alcohol
ß 2013 Elsevier B.V. All rights reserved.
Hexafluoroisopropanol (HFIP)
SBA-15 nanoreactor
Multicomponent reaction
Thioxo-thiophenecarboxylate
1. Introduction
However, this method has many drawbacks such as using non-
stoichiometric amount of carbon disulfide, tedious work-up,
In last decade, ordered mesoporous silicas as nanoreactor such
as SBA-15 and its functionalized family (RX@SBA-15) with a
tunable pore structure and tailored composition have received
considerable interest in organic synthesis [1]. The strategy of using
unfunctionalized SBA-15 as catalyst, which has advantage of
porous mesochannels as nanoreactor, is typically easier than
functionalization or modification of SBA-15 to RX@SBA-15 while it
needs fewer synthetic steps [2]. On the other hand, fluorinated
alcohols (RfOH) demonstrate their unique properties as solvents/
co-solvents or additives in the organic synthesis [3]. The
availability of RfOHs has initiated a boom in their applications
in the past decade [2,3]. The utilization of RfOH as a reaction
generation of large amounts of CS2 waste, low yields of products,
and long reaction times. The development and improvement of
novel synthesis methods for 5-oxo-2-thioxo-3-thiophenecarbox-
ylates (rhodanine) are still attractive goals because of their
numerous biological and chemical activities including the inhibi-
tion of numerous targets such as PMT1 manosyl transferase [5],
PRL-3 and JSP-1 phosphatases [6].
Following to our recent success in applying the TFE/SBA-15
nanoreactor in the imidazole preparation [2] an active and
recyclable HFIP-medium (1,1,1,3,3,3-hexafluoro-2-propanol or
hexafluoroisopropanol) catalyst was applied in the present
research for synthesis of alkyl rhodanines under mild reaction
conditions. While this approach showed reusability for both HFIP
and SBA-15, it minimized the wastes and side products (Scheme 1).
´
´
medium or co-solvent was highlighted by Begue et al. and
Uneyama. Based on their unique nature acid-catalyzed organic
process can be done in the fluorinated alcohols [3].
In our recent investigation, the reaction of dialkyl acetylene-
dicarboxylate with carbon disulfide in the presence of alkyl amine
derivatives led to the formation of alkyl rhodanine derivatives [4].
2. Results and discussion
We developed synthetic methods for biologically interesting
molecules via multicomponent reactions and nanocatalysts [7].
The challenge in this field was developed by an efficient and
suitable method instead of synthesizing these heterocycles in the
presence of polar solvents such as DMF, and DMSO, which lead to
complex isolation and recovery procedures. In this paper, we
present the results of an extended investigation on the activity of
* Corresponding author. Tel.: +98 421 2274893; fax: +98 421 2276066.
(S. Rostamnia).
1
Tel.: +98 421 2274893; fax: +98 421 2276066.
0022-1139/$ – see front matter ß 2013 Elsevier B.V. All rights reserved.