Metal and metal-free photocatalysts: mechanistic approach and application as photoinitiators of photopolymerization

• Jacques Lalevée,
• Sofia Telitel,
• Pu Xiao,
• Marc Lepeltier,
• Frédéric Dumur,
• Fabrice Morlet-Savary,
• Didier Gigmes and
• Jean-Pierre Fouassier

Beilstein J. Org. Chem. 2014, 10, 863–876, doi:10.3762/bjoc.10.83

• (JASCO FTIR 4100) at about 1630 cm−1 as in [15]. iv) The ring opening polymerization of epoxides: The photosensitive formulations were deposited (25 µm thick) on a BaF2 pellet under air. The evolution of the epoxy group content was continuously followed by real time FTIR spectroscopy (JASCO FTIR 4100) at

• in an oxidative cycle in combination with Ph2I+ and NVK. The polymerization initiating ability of the Ir(piq)2(tmd)/Ph2I+/NVK system The polymerization profile for the ring-opening polymerization of EPOX using a Ir(piq)2(tmd)/Ph2I+/NVK initiating system upon a laser diode at 532 nm is depicted in

Polyglycerol-functionalized nanodiamond as a platform for gene delivery: Derivatization, characterization, and hybridization with DNA

• Li Zhao,
• Yuki Nakae,
• Hongmei Qin,
• Tadamasa Ito,
• Takahide Kimura,
• Hideto Kojima,
• Lawrence Chan and
• Naoki Komatsu

Beilstein J. Org. Chem. 2014, 10, 707–713, doi:10.3762/bjoc.10.64

• vector consisting of nanodiamond, polyglycerol, and basic polypeptide (ND-PG-BPP) has been designed, synthesized, and characterized. The ND-PG-BPP was synthesized by PG functionalization of ND through ring-opening polymerization of glycidol on the ND surface, multistep organic transformations (–OH → –OTs

• , which is covered with organic functional groups [12]. Quite recently, we found that ring-opening polymerization of glycidol is initiated at the oxygen-containing functionalities, hydroxy and carboxy groups, on the ND surface to give polyglycerol- (PG) grafted ND with 30 nm size (ND30-PG) [13]. The

• ) effect, ND with 50 nm size was chosen for this study. The ND50 was covalently functionalized with hyperbranched PG through ring-opening polymerization of glycidol according to the procedure we reported previously [13]. The resulting ND50-PG was characterized qualitatively by FTIR and 1H NMR, and

N,N'-(Hexane-1,6-diyl)bis(4-methyl-N-(oxiran-2-ylmethyl)benzenesulfonamide): Synthesis via cyclodextrin mediated N-alkylation in aqueous solution and further Prilezhaev epoxidation

• Julian Fischer,
• Simon Millan and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 2834–2840, doi:10.3762/bjoc.9.318

• was reacted in a ring-opening polymerization with the primary amine α-amino-ε-caprolactam (8). 8 was synthesized by cyclization of lysine (7) (Scheme 2). Hence, an increase of the reactivity of the primary amino group towards the epoxide function compared to the amino groups in native lysine was

• are relatively comparable to a mixture of BADGE with 8, whereby the observed differences can be caused by different reactivity of the oxirane moieties or unequal solubility of the respective diepoxide with 8. By means of IR spectroscopy, ring opening polymerization of epoxides with amines can be

New core-pyrene π structure organophotocatalysts usable as highly efficient photoinitiators

• Sofia Telitel,
• Frédéric Dumur,
• Thomas Faury,
• Bernadette Graff,
• Mohamad-Ali Tehfe,
• Didier Gigmes,
• Jean-Pierre Fouassier and
• Jacques Lalevée

Beilstein J. Org. Chem. 2013, 9, 877–890, doi:10.3762/bjoc.9.101

• Eox(Py_9) > Ered(Iod) (Table 1). The formation of radical cations can be worthwhile to initiate cationic polymerization at room temperature (see below). Ability of the different pyrene structures in photopolymerization reactions Cationic photopolymerization (CP) The ring-opening polymerization

• r5 and r6 and (iv) the ability of Co_Py•+ to initiate a ring-opening polymerization process. Structure–reactivity relationships for the different derivatives can hardly be extracted. This is probably ascribed to a strong interplay between (i) to (iv). A cationic photopolymerization profile of EPOX

• . The large choice of Co_Pys should allow for studying the effect of the core on the MO coupling and the resulting absorption properties. The activity of these Co_Py compounds in the FRP of acrylates and the FRPCP (and eventually the cationic polymerization CP) of epoxides through a ring-opening

1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ε-caprolactone and rac-lactide under solvent-free conditions

• Astrid Hoppe,
• Faten Sadaka,
• Claire-Hélène Brachais,
• Gilles Boni,
• Jean-Pierre Couvercelle and
• Laurent Plasseraud

Beilstein J. Org. Chem. 2013, 9, 647–654, doi:10.3762/bjoc.9.73

• Astrid Hoppe Faten Sadaka Claire-Helene Brachais Gilles Boni Jean-Pierre Couvercelle Laurent Plasseraud Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR CNRS 6302, Avenue A. Savary, BP 47870, F-21078 Dijon, France 10.3762/bjoc.9.73 Abstract The ring-opening polymerization

• the desired polymers. Heating in vacuo is more efficient for the ROP of ε-caprolactone for which a conversion of 100% was always observed. However the highest conversion for rac-lactide of 83% was achieved by using NaBPh4 as decarboxylating agent. Alcohols 1–4 initiate the ring-opening polymerization

• monomer-activated mechanism for the ring-opening polymerization of ε-caprolactone and rac-lactide (Scheme 2) [20][27][28][33][49]. Conclusion In this contribution, we have reported that BMIM-2-CO2 can be an active precatalyst for the solvent-free ring-opening polymerization of ε-caprolactone and rac

Design and synthesis of a photoswitchable guanidine catalyst

• Philipp Viehmann and
• Stefan Hecht

Beilstein J. Org. Chem. 2012, 8, 1825–1830, doi:10.3762/bjoc.8.209

• photochromic properties demonstrated the reversible switchability of its photosensitive azobenzene moiety. Its activity in the ring-opening polymerization (ROP) of rac-lactide was investigated as well. The obtained results are discussed, and an additional guanidine was synthesized and utilized in the ROP of

• rac-lactide in order to explain the findings. Keywords: azobenzenes; guanidines; molecular switches; organocatalysis; photochromism; ring opening polymerization; Introduction The macroscopic properties of a given polymer, e.g., the glass-transition temperature, morphology, density and tensile

• incorporated into the catalyst system [6][7][8][9][10][11][12][13]. To the best of our knowledge, successful examples of photoswitchable catalysts for the ring-opening polymerization (ROP) of lactide have not been reported thus far, although a remarkable example of a photocaged system has been reported [14

Influence of cyclodextrin on the solubility of a classically prepared 2-vinylcyclopropane macromonomer in aqueous solution

• Helmut Ritter,
• Jia Cheng and
• Monir Tabatabai

Beilstein J. Org. Chem. 2012, 8, 1528–1535, doi:10.3762/bjoc.8.173

• ]. Generally, 2-vinylcyclopropane monomers (2-VCPs) are known for their low volumetric shrinkage or even small expansion during free radical ring-opening polymerization (Scheme 1) [26][27][28]. However, this behavior is not in focus of the present work. The resulting polymer bears mainly 1,5-ring-opened units

• . Therefore, we came to the conclusion that the Me2-β-CD ring preferably includes the vinylcyclopropane unit instead of the isopropyl unit. The supramolecular complex 7 shows the typical LCST behavior (31.7 °C) of poly(NiPAAm) (Figure 4). After free radical initiated ring-opening polymerization of 5, a

• ring-opening polymerization of 2-VCPs (In: initiator) [29][30][31]. Synthesis of diethyl 2-vinyl-1,1-cyclopropanedicarboxylate [33]. Two-step synthesis of the macromonomer 5 (In: Initiator, TEA: triethylamine). Homo- and copolymerization of macromonomer 5. Properties of synthesized macromonomers and

Restructuring polymers via nanoconfinement and subsequent release

• Alan E. Tonelli

Beilstein J. Org. Chem. 2012, 8, 1318–1332, doi:10.3762/bjoc.8.151

• -nucleated PET not only possesses improved properties, but contains no incompatible additives, and so may be readily recycled. Coalesced block copolymers The triblock copolymer PCL-PPG-PCL, with noncrystallizable central poly(propylene oxide blocks), was synthesized by coordinated ring-opening polymerization

Formation of epoxide-amine oligo-adducts as OH-functionalized initiators for the ring-opening polymerization of ε-caprolactone

• Julia Theis and
• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, 938–944, doi:10.3762/bjoc.6.105

• were used as the initiator for the ring-opening polymerization of ε-caprolactone to produce a graft copolymer. Keywords: addition oligomerization; epoxide-amine adducts; microwave; ring-opening polymerization; transfer hydrogenation; Introduction In the last decade the use of microwave (MW

• higher molecular weight products. Ring-opening polymerization of ε-caprolactone The epoxide-amine adduct 4 was used for preparation of graft copolymer 6 via ring-opening polymerization (ROP) of ε-caprolactone (ε-CL, 5), where the secondary hydroxy groups of 4 act as the initiator. This ROP was catalyzed

• shows a melting point (Tm) at 50 °C while PCL homopolymer crystallizes at about 55 °C. Obviously the backbone of copolymer 6 reduces the crystalline order. Conclusion A graft copolymer (6) was synthesized via ring-opening polymerization of ε-caprolactone using an epoxide-amine addition product 4 as an

Synthesis and crystal structures of multifunctional tosylates as basis for star-shaped poly(2-ethyl-2-oxazoline)s

• Richard Hoogenboom,
• Martin W. M. Fijten,
• Guido Kickelbick and
• Ulrich S. Schubert

Beilstein J. Org. Chem. 2010, 6, 773–783, doi:10.3762/bjoc.6.96

• of well-defined polymer architectures is of major importance for the development of complex functional materials. In this contribution, we discuss the synthesis of a range of multifunctional star-shaped tosylates as potential initiators for the living cationic ring-opening polymerization (CROP) of 2

• might cause side reactions during the polymerizations. Subsequently, this tetrafunctional initiator was applied for the microwave-assisted cationic ring-opening polymerization of EtOx. The polymerization of EtOx with TetraTos-B as initiator was performed with 2 M monomer concentration in CH3CN at 140 °C

• structures of di-, tetra- and hexa-tosylates were centrosymmetric with ideal space filling packing. The use of tetra- and hexa-tosylates, based on (di)pentaerythritol as initiators for the living cationic ring-opening polymerization (CROP) of 2-ethyl-2-oxazoline, resulted in very slow initiation and ill

Novel tetracyclic structures from the synthesis of thiolactone-isatin hybrids

• Renate Hazel Hans,
• Hong Su and
• Kelly Chibale

Beilstein J. Org. Chem. 2010, 6, No. 78, doi:10.3762/bjoc.6.78

• . Moreover, its presence in a number of proprietary molecules and synthetic drugs is noteworthy [17]. Alkylation of 5, as shown in Scheme 1, is a common route towards diverse thiolactomycin analogues. A literature review revealed that γ-thiolactones are prone to undergo ring-opening polymerization under the

Poly(glycolide) multi-arm star polymers: Improved solubility via limited arm length

• Florian K. Wolf,
• Anna M. Fischer and
• Holger Frey

Beilstein J. Org. Chem. 2010, 6, No. 67, doi:10.3762/bjoc.6.67

• which significantly exceed the molecular weight of processable oligomeric linear PGA (<1000 g/mol). This was achieved by the use of a multifunctional hyperbranched polyglycerol (PG) macroinitiator and the tin(II)-2-ethylhexanoate catalyzed ring-opening polymerization of glycolide in the melt. With this

• exchange equilibrium which is a well-known phenomenon in oxyanionic polymerizations. In the second step, the polyether-polyols were used as macroinitiators for the ring-opening polymerization of glycolide via Sn(Oct)2 catalysis. All polymerization experiments were carried out in bulk (with a minimum of

Synthesis and crossover reaction of TEMPO containing block copolymer via ROMP

• Olubummo Adekunle,
• Susanne Tanner and
• Wolfgang H. Binder

Beilstein J. Org. Chem. 2010, 6, No. 59, doi:10.3762/bjoc.6.59

•  = tricyclohexylphosphine), [(H2IMes)(PCy3)Cl2Ru(3-phenylinden-1-ylidene)] U2 (H2IMes = 1,3-bis(mesityl)-2-imidazolidinylidene), [(H2IMes)(py)Cl2Ru(3-phenylinden-1-ylidene)] U3 (py = pyridine or 3-bromopyridine) via ring opening polymerization (ROMP). The crossover reaction and the polymerization kinetics were investigated

New amphiphilic glycopolymers by click functionalization of random copolymers – application to the colloidal stabilisation of polymer nanoparticles and their interaction with concanavalin A lectin

• Otman Otman,
• Paul Boullanger,
• Eric Drockenmuller and
• Thierry Hamaide

Beilstein J. Org. Chem. 2010, 6, No. 58, doi:10.3762/bjoc.6.58

• backbone. Thus, polycaprolactones (PCL) functionalized with galactopyranose end-groups have been synthesized by ring opening polymerization and used for the stabilization of PCL nanoparticles [4]. Glucose or cellobiose moieties have been grafted at both ends of short PDMS chains and used as polymer