The thiazolo [5,4-d]thiazole fused (bi)heterocycle is an electron deficient system with high oxidative stability and a rigid planar structure, enabling efficient intermolecular p-p overlap. The parent thiazolo [5,4d]thiazole moiety hence already possesses some appealing features towards applications in organic electronics. Moreover, aryl-functionalized thiazolo [5,4-d]thiazole derivatives -expanding the conjugated backbone of the semiconducting material -are easily prepared. Surprisingly, interest in thiazolo [5,4d]thiazole-based materials has been rather low, until quite recently, when the high potential of these molecules was widely recognized, notably in the field of organic photovoltaics. Despite the almost exponential growth of activity, the synthetic chemistry behind these molecules has only been explored to a minor extent and there is plenty of room for improvement and broadening of the material scope. In this review, an overview of the currently available synthetic methods and the range of materials prepared to date, together with their basic material properties and main applications, is provided, with the aim to facilitate and stimulate further progress in thiazolo [5,4-d]thiazole-based materials science.

Donor-acceptor type light-harvesting molecular wires are covalently attached to a boron-doped diamond surface via a combination of diazonium electrografting and Suzuki cross-coupling. For the Suzuki reaction, various catalytic systems are compared with respect to their imposed surface coverage. Combining 2dicyclohexylphosphino-2 0 ,6 0-dimethoxybiphenyl (SPhos) and Pd(0), the diamond coverage improves considerably (by 98%) as compared to the standard tetrakis(triphenylphosphine)palladium(0) (Pd(PPh 3) 4) catalyst. As the energy levels between the molecular chromophores and the diamond film align well, the sophisticated functionalized diamond surfaces present a first step towards the development of fully carbon-based devices for light to electricity conversion.

N3 dye molecules [cis-bis(isothiocyanato)-

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Solution-phase combinatorial synthesis of (2S,4S)-4-acylamino-5-oxopyrrolidine-2-carboxamides was studied. First, di-tert-butyl (2S,4S)-4-amino-5-oxopyrrolidine-1,2-dicarboxylate hydrochloride was prepared as the key intermediate in five steps from (S)-pyroglutamic acid. Acylation of the amino group followed by acidolytic deprotection gave (2S,4S)-4-acylamino-5-oxopyrrolidine-2-carboxylic acids, which were then coupled with amines to furnish a library of (2S,4S)-4-acylamino-5-oxopyrrolidine-2-carboxamides. Four coupling reagents, BPC, EEDQ, TBTU, and PFTU, were tested for the amidation reactions in the final step. Amidations with EEDQ and TBTU led to the desired carboxamides. On the other hand, BPC and PFTU were not suited, since diketopiperazines were sometimes obtained instead of the desired carboxamides.

A series of racemic dipodazine analogues 9 were prepared in 22 -80% yield from (3Z,6RS)-3-[(dimethylamino)methylidene]-6-methyl-1-(phenylmethyl)piperazine-2,5-dione (7) (Scheme 1), which was prepared in four steps from (RS)-alanine methyl ester hydrochloride. The preparation of nonracemic 7 from (S)-alanine methyl ester hydrochloride failed, since the introduction of the enamino functionality at position 3 of the precursor 6 was accompanied by almost complete racemization.Introduction. -Many marine natural products with potent pharmacological activities contain an indole nucleus [1]. Such indole derivatives are, e.g., aplysinopsins (1; Fig. 1), which have attracted considerable interest due to their cytotoxicity towards cancer cells and their ability to affect neurotransmitters [2]. Recently, the nortopsentins and meridianins (2), another series of indole alkaloids with interesting antitumor properties, have been isolated from the sponge Spongosorites ruetzleri, and from tunicate Aplidium meridianum [3]. Structurally, the meridianins comprise a brominated and/ or hydroxylated indole nucleus bearing a 2-aminopyrimidine substituent at the 3-position [4], and they are potent inhibitors of several protein kinases [5]. Other interesting biologically active indole alkaloids are 1) tryptophan-dehydrobutyrine diketopiperazine (TDD; 3) [6], a fungal metabolite isolated from Streptomyces spectabilis and Streptomyces sp. M1513-bF5; 2) barettin (4) [7], isolated from the marine sponge Geodia barretti, a diketopiperazine condensation product of 6-bromodehydrotryptophan and arginine; as well as 3) dipodazine (5) [8], a diketopiperazine derivative composed of dehydrotryptophan and glycine, which has been isolated from Penicillium dipodomyis and meat-associated P. nalgiovese. The syntheses of compounds 3 -5 and their analogues include condensation of 1H-indole-3-carbaldehyde with piperazine-2,5-dione derivatives as the key-step [6 -8].Alkyl 3-(dimethylamino)propenoates and related enaminones have been recently used as building blocks for the preparation of dehydro-alanine derivatives and many heterocyclic systems such as fused pyridines, pyrimidines, pyranones, and other compounds, including some natural products (e.g., indole alkaloids) and their synthetic analogues [9]. Various chiral analogues of 3-(dimethylamino)propenoates have also been prepared from commercially available, enantiomerically pure starting materials such as a-amino acids and (+)-camphor, and were employed as key intermediates and reagents in the synthesis of 1) functionalized heterocycles, e.g., 3-heteroarylalanine derivatives and related compounds, 2) heterocyclic analogues of dipeptides, and 3) terpene-func-