A- polymer-supported

Monoprotection of a symmetrical diol can be effected by reaction with a polymer-supported phenylacetyl chloride. The free hydroxyl group is then converted to an ether and the phenylacetate cleaved by aqueous ammonia-dioxane, 48 h. ... 

A polymer-supported 1,2-diol has also been developed. ... 

A polymer-supported sulfonamide, prepared from an amino acid activated ester and a polystyrene-sulfonamide, is stable to acidic hydrolysis (CF3COOH HBr/ HOAc). It is cleaved by the safety-catch method shown below. ... 

Desyl bromide, DBU, benzene, reflux, 57-95% yield. A polymer-supported version of this ester has been prepared. ... 

A polymer-supported sulfonamide, prepared from an amino acid activated ester... 

A more effecdve catalyst for the Hetuy reacdon is a polymer-supported base such as amberlyst A-31. Various fi-nitro alcohols can be obtained v/ith the help of amberlyst v/ith or without solvent fEq, 3,14, A recent report claims that amberlite IRA-430 COH-formi or DOWEX-1 COH-formi is more effecdve for the Henry reacdon than amberlyst A-31/ Poly-... 

The use of a polymeric support also affords a unique opportunity to control independently the variables that may affect the chiral recognition process, which is hard to achieve with silica. For example, the type and number of reactive sites can be easily adjusted with a polymer support. We recently reported an extensive study of the... 

A novel use of the salt [BMIM][PFg] is to enhance microwave absorption and hence accelerate the rate of a reaction. Ley found that [BMIM][PFg] enhanced the rate of the microwave-promoted thionation of amides by a polymer-supported thionating agent [64]. 

Under certain condition, however, reactions are still preferably conducted in solution. This is the case e.g., for heterogeneous reactions and for conversions, which deliver complex product mixtures. In the latter case, further conversion of this mixture on the solid support is not desirable. In these instances, the combination of solution chemistry with polymer-assisted conversions can be an advantageous solution. Polymer-assisted synthesis in solution employs the polymer matrix either as a scavenger or for polymeric reagents. In both cases the virtues of solution phase and solid supported chemistry are ideally combined allowing for the preparation of pure products by filtration of the reactive resin. If several reactive polymers are used sequentially, multi-step syntheses can be conducted in a polymer-supported manner in solution as well. As a further advantage, many reactive polymers can be recycled for multiple use. 

Solid phase synthesis is a polymer-supported or solid-supported synthesis, i.e., stepwise construction of product molecules attached to an insoluble organic or inorganic polymer. 

The oxidation of sulphoxides with peracid resins occurs rapidly and quantitatively at 20°C using dioxane as solvent150. Vanadium(V), generated on a polymer support by treatment of vanadium(IV) with a hydroperoxide (equation 49) may be used to oxidize successfully sulphoxides to sulphones in very good yields151. 

A novel and versatile method for preparing polymer-supported reactive dienes was recently developed by Smith [26]. PS-DES (polystyrene diethyl-silane) resin 28 treated with trifluoromethanesulfonic acid was converted to a polymer-supported silyl triflate 29 and then functionalized with enolizable a,jS-unsaturated aldehydes and ketones to form silyloxydienes 30 and 31 (Scheme 4.4). These reactive dienes were then trapped with dienophiles and the Diels Alder adducts were electrophilically cleaved with a solution of TFA. 

A polymer-supported silyl triflate and subsequent functionalization synthesis and solid-phase Diels-Alder reactions of silyloxydienes [25]... 

An alternative approach towards the PASP synthesis of isocyanides was developed by Bradley [100,101]. It involved the use of a polymer-supported sul-fonyl chloride in the presence of base to afford the dehydration of formamides (Scheme 21). The formamides required could be easily prepared by reaction of the corresponding amines with a formylated benzotriazole resin. Opti-... 

Kim and Park et al. have reported a polymer-supported derivative (4), which, together with the enzyme, can be recycled and reused [27]. 

A strategy involving sequential 1,3-dipolar cycloadditions has been reported for the synthesis of novel bis-isoxazolo substituted piperidines 192a and 192b (Eqs. 18 and 19) [53]. It consists of the Michael addition of an unsaturated alkox-ide 185 to )3-nitrostyrene 184 followed by an INOC or ISOC reaction to provide isoxazolines 187-189 (Eq. 18 and Table 18). A polymer supported acyl chloride... 

A polymer-supported version of our optimal ligand was also developed [52]. Its preparation involves attachment of aziridine carbinols to polymer-bound triphenylchloromethane (Scheme 40). This polymer-bound ligand 53 was almost equally effective in the enantioselective addition of diethylzinc to aromatic and aliphatic aldehydes with ee s ranging from 77-97% for the latter type of substrate [52]. It is of practical interest that this polymer-supported ligand could be reused without losing much of its efficiency. 

Moberg et al. [146] modified further the bis(pyridylamide) ligand described by Trost for the preparation of a polymer-supported pyridylamide (113 in Scheme 60) for the microwave-accelerated molybdenum-catalyzed al-lylic alkylation. TentaGel resin was tested in the presence of high concentrations of reactants and gave, after a 30 min reaction, total conversion in the... 

All the Ru-based racemization catalysts described earUer are air-sensitive and thus difficult to reuse. We found that a modified Ru complex 7 was air-stable and recyclable, in particular, in a polymer-supported form 8. The racemization of secondary alcohols with 7 took place equally well under both oxygen and argon atmospheres. The subsequent DKRs of several alcohols using 7 or 8 under aerobic... 

If molybdenum(VI) is generated by treatment of a polymer-supported complex containing molybdenum(V) with a hydroperoxide, then this polymer-supported oxidant may also be used to prepare sulphones from sulphoxides. In this case the yield is not good unless the sulphoxide is repeatedly passed through a column containing the oxidant or the reaction is performed by stirring the polymer and the sulphoxide together at 56 °C for 16 hours . ... 

Preparation of Esters by Use of a Polymer-Supported Carboxylic Acid Imidazolide... 

Tetrazolide-activated nucleotide phosphites have been employed in the synthesis of polynucleotides on a polymer support using methoxybistetrazolylphosphine as phosphi-tylating agent [104]... 

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