Open organocatalytic

For the related organocatalytic ring-opening of oxazinones, see Berkessel A, Cleemann F, Mukherjee S (2005) Angew Chem Int Ed 44 7466-7469... 

Finally, a highly efficient organocatalytic asymmetric approach was described by Gong et al. in 2006, using chiral phosphoric acids as catalysts. These results opened a window for the development of new optically active DHPMs synthesis (Scheme 19) [96, 97]. More recently, chiral organocatalysts such as Cinchona... 

Casas J, Persson PV, Iversen T, Cordova A (2004) Direct organocatalytic ring-opening polymerizations of lactones. Adv Synth Catal 346 1087-1089... 

Kamber NE, Jeong W, Waymouth RM, Pratt RC, Lohmeijer BGG, Hedrick JL (2007) Organocatalytic ring-opening polymerization. Chem Rev 107 5813-5840... 

Connor EE, Nyce GW, Myers M, Mock A, Hedrick JL (2002) First example of N-heterocyclic carbenes as catalysts for living polymerization organocatalytic ring-opening polymerization of cyclic esters. J Am Chem Soc 124 914-915... 

Kamber NE, Jeong W, Gonzales S, Hedrick JL, Waymouth RM (2009) N-Heterocyclic carbenes for the organocatalytic ring-opening polymerization of a-caprolactone. Macromolecules 42 1634-1639... 

Figure 2.14 Organocatalytic ring-opening polymerisation of lactide with a hydroxyethyl functionalised NhIC compound as catalyst.

A series of organocatalytic solvent free reactions have recently been performed using An asymmetric alkaloid-mediated opening of a cyclic... 

Organocatalytic ring-opening polymerization involving lactones, morpholine-2,6-diones, cyclosiloxanes, and oxadisilacyclohexanes as monomers and/or heterocyclic carbenes as catalysts 07CRV5813. 

Organocatalytic ring-opening polymerization of oxadisilacyclohexanes and cyclosiloxanes 07CRV5813. 

Various biodegradable polycarbonate(s) (PC) polymers have been fabricated via the organocatalytic ring-opening polymerisation of functional cyclic carbonate monomers, which were quarternised to create cationic polymers with various pendent structures such as alkyl, aromatic and imidazolinium (Figure 8.4). These polymers have shown excellent antimicrobial properties and haemolytic characteristics when assayed using rat red blood cells [98]. 

In contrast, here a bifunctional initiator is employed and the polymerization order of the two blocks is inverted In a first step, the styrene block is synthesized by atom transfer radical polymerization (ATRP) followed by the addition of lactide via the recently developed organocatalytic ring-opening polymerization, as depicted in Fig. 3.1 [4, 5]. This synthesis route reduces the involved steps and enables a simplified and time-efficient preparation of copolymers with different block compositions. Importantly, both polymerization techniques offer precise and robust control over the copolymer composition, which is an essential requirement to reliably target the double-gyroid s narrow location in phase space [6]. 

Coordination-insertion, anionic, cationic, and nucleophilic polymerization are the most frequently reported controlled ring-opening polymerization (ROP) of cyclic monomers in the literature [37, 38]. The coordination-insertion and nucleophilic polymerization are undoubtedly the most efficient and general methods reported so far for the ROP of lactones, with cationic and anionic polymerization being much less investigated. While coordination-insertion polymerization uses metal-alkoxides and related complexes as catalysts, the organocatalytic nucleophilic polymerization is a metal-free approach to ROP. 

The most widely applied catalyst systems in organocatalytic ROP include N-heterocyclic carbenes [62, 64, 67], guanidine and amidine bases [51,65] and phosphorane-based compounds [68,69]. Strong organic acids are excluded from this section as their mechanism follows the one described for cationic ring-opening polymerisations [70, 71]. 

Based on enantioselective epoxidation and subsequent ring opening and closing, the so-called Achmatowicz reaction was developed. This is an organocatalytic one-pot cascade for the annulation of a,(J-unsaturated aldehydes, hydrogen peroxide, p-carbonyl compounds and NBS, which furnish optically active 3-pyrones. Other chiral heterocycles were also assembled by organocatalytic cascade reactions using diaiylprolinol silyl ethers as catalysts. ... 

The initial products of organocatalytic epoxidation and aziridination can be ring opened with methoxide. In this way, tra/zs-dihydrorgrlation and frans-aminohydrorq lation of a,p-unsaturated aldehydes was achieved (Scheme 8.44). ... 

Scheme 1.5 Wang s organocatalytic cyclopropanation with unexpected ring-opened product...

Recently, organocatalytic enantioselective transformations of the densely functionalized Baylis-Hillman adducts and their derivatives have gained continuous interest, which opened a new access to the synthesis of optically active functionalized structures [125]. BH adducts and their derivatives include BH alcohols, BH acetates, BH carbonates, and halides, among which BH carbonates are more reactive and hence have received much attention recently. In this section, we will review all the reactions that appeared in the last few years with the use of BH carbonates as substrates. 

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