TETRAHEDRON LETTERS Tetrahedron Letters 44 (2003) 5777–5780 Pergamon Facile and reversible synthesis of an acidic water-soluble poly(amidoamine) fullerodendrimer Yutaka Takaguchi, a, * Yuuki Sako, b Yasushi Yanagimoto, a Sadao Tsuboi, a Jiro Motoyoshiya, b Hiromu Aoyama, b Takatsugu Wakahara c and Takeshi Akasaka c a Faculty of Environmental Science and Technology, Okayama University, Okayama, Okayama 700 -8530, Japan b Faculty of Textile Science & Technology, Shinshu University, Ueda, Nagano 386 -8567, Japan c Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki 305 -8577, Japan Received 28 April 2003; revised 6 June 2003; accepted 9 June 2003 Abstract—Water-soluble fullerodendrimer was obtained by the use of a Diels–Alder reaction of C 60 with a newly designed anthryl dendron under an extremely mild condition in 70% yield, which is more than five times as high as the yield described in our previous report. © 2003 Elsevier Ltd. All rights reserved. Fullerene-based derivatives have been attracting a great interest in the field of structural and synthetic organic chemistry. 1 In particular, there is an increasing focus on developing applications for fullerene-functionalized dendrimers, fullerodendrimers, because of a variety of interesting features in supramolecular chemistry and material science. 2 However, the chemistry of dendrimer containing a C 60 core had been very much limited, because only a few efficient reactions in construction of fullerodendrimer were reported. 1b,2–6 The elegant and pioneering studies reported by Fre ´chet, 3 Hirsch, 4 Diederich 1b and Nierengarten 1b,5 are not so easy to be performed by almost chemist. Recently, we have described the reversible formation of fullerodendrimers by the use of a Diels–Alder reaction of C 60 with anthryl dendron (1). 7 During our studies on the reactivity of the anthracene derivatives with C 60 , we found that the yield was dramatically improved by changing the substituent on the anthracene moiety. This paper describes the facile preparation and characterization of a water-solu- ble poly(amidoamine) fullerodendrimer (2). In order to improve on the yield of fullerodendrimer which can be obtained by a Diels–Alder reaction, we refine upon the molecular design of anthracenyl den- dron 1 which was employed in a previous paper. 7 First, a bulky dendritic substituent was moved from 9-posi- tion to 2-position, since it might not be preferred at a bridge head of [4+2]cycloadduct arisen from 9-substi- tuted anthracene derivatives. Second, we used an electron-withdrawing group as a tether between an anthracene and a dendron wedge, because the cycloadducts of C 60 with electron-deficient dienes were found to be quite stable. 8 This newly designed anthryl dendron (3) was actually prepared according to our strategy previously reported (Scheme 1). 9 A focal point of dendron, compound (4), was obtained by reaction of 2-anthracenecarboxylic acid methyl ester (5) with ethylenediamine. Subsequently, treatment of 4 with methyl acrylate produced a dendron (3a) in 85% yield. This two-step process can be repeated to prepare (3b) and (3c) in 85 and 50% yields, respectively. The structures of 3a, 3b, and 3c were confirmed by 1 H, 13 C Keywords : fullerodendrimer; anthracene; cycloaddition; water-soluble fullerene. * Corresponding author. Tel.: +81-86251-8903; fax: +81-86251-8903. 0040-4039/$ - see front matter © 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0040-4039(03)01425-4