We have found a simple and novel synthetic method for obtaining a chiral polymer from an achiral monomer by using a chiral catalytic system. The chirality of the polymer was caused only by a one-handed helical backbone, and the polymer had no other chiral structures in the side groups. In addition, the helical conformation was stable in solution by itself. This is the first example of helix-sense-selective polymerization of a substituted acetylene. The stability of the helicity was found to be caused by intramolecular hydrogen bonds.

A novel, highly selective photocyclic aromatization (SCAT) of π-conjugated polymers from phenylacetylene having two hydroxyl groups to exclusively yield a 1,3,5-trisubstituted benzene derivative was developed, and its success was confirmed by (1)H NMR, GPC, and TOF-MS. The SCAT reaction has many unique characteristics. (1) It is a quantitative reaction: it gave only the corresponding cyclic trimer, i.e., a 1,3,5-trisubstituted benzene derivative, quantitatively (100%). No byproducts were produced under the best conditions. (2) It is an intramolecular reaction: it occurred between three adjacent monomer units in one macromolecule. (3) It is a stereospecific and topochemical or template reaction: the reactivity strongly depended on the configuration and conformation of the starting polymer substrates. (4) It is a photoreaction: high selectivity (100%) was observed only by the use of visible light irradiation, not by heating. (5) It is a solid-state reaction: high selectivity (100%) was observed only in the solid state, not in solution. In addition, (6) the resulting cyclic trimers could form a self-supporting membrane, despite their low molecular weights. This new approach resulted in a new class of supramolecular polymers consisting of a 1,3,5-trisubstituted benzene derivative, numbers of which were linearly linked by hydrogen bonds and stacked benzene derivatives. Since SCAT has such high selectivities and is useful for the preparation of a self-supporting supramolecular polymer membrane, many applications can be expected.

No abstract

IntroductionMyelodysplastic syndrome (MDS) is a slowly progressing leukemic disorder that predominantly affects elderly people. 1,2 Individuals with MDS exhibit cytopenia in at least one lineage of peripheral blood (PB) cells. However, the bone marrow (BM) of many affected individuals is hyper-to normocellular, suggesting the presence of ineffective hematopoiesis. Another characteristic feature of MDS is the dysplasia of at least one lineage (myeloid, erythroid, or megakaryocyte-platelet lineage) of BM cells, such as neutrophils with pseudo-Pelger anomaly, hypersegmented neutrophils, ringed sideroblasts, and micromegakaryocytes. 3 The clinical course of MDS can be divided into several phases. Patients in the indolent, chronic phase exhibit a decrease in the number of PB cells and are diagnosed with either refractory anemia (RA) or RA with ringed sideroblasts (RARS). Individuals with dysplastic change in BM and monocytosis in PB are diagnosed with chronic myelomonocytic leukemia (CMMoL). After a variable interval, however, some individuals with MDS undergo a progressive transformation to overt leukemia. As the number of blast cells increases, the patients are diagnosed with RA with an excess of blasts (RAEB; 5%-19% blasts in BM), RAEB in transformation (RAEB-t; 20%-29% blasts in BM), and, finally, MDS-associated acute leukemia (Ͼ 20% blasts in BM).MDS-associated leukemia is rarely cured by conventional chemotherapy. Intensive treatment with anticancer drugs often results in prolonged myelosuppression, which is one of the main causes of disease-related death. 4 Individuals with acute leukemia that results from MDS therefore have a poor prognosis, which contrasts with the somewhat better outcome of de novo acute myeloid leukemia (AML) in this older group of patients. It is thus essential to differentiate MDS-associated leukemia from de novo AML to select the optimal therapeutic strategy.This task is complicated, however, by the fact that some patients with de novo AML may exhibit dysplastic changes in BM during the course of their disease. [5][6][7] It is thus extremely difficult to diagnose elderly individuals with overt leukemia if their BM exhibits dysplasia. The occurrence of a period of cytopenia before the development of leukemia indicates that the patient should be treated for MDS-associated leukemia. Without the clinical history, however, there are currently few other criteria with which to differentiate MDS-associated leukemia from de novo AML with The development of DNA microarrays or DNA chips has revolutionized the analysis of gene expression profiles. Such DNA microarrays can contain tens of thousands of test complementary DNAs (cDNAs) or oligonucleotides and, with a single hybridization step, allow a systematic comparison of the expression of the corresponding genes between 2 given samples. 8 The completion of the human genome sequencing project will increase further the analytical power of this technology. The use of DNA microarrays has already allowed the identification of candidate mammalian genes ...