Wang aldehyde resin

Hanessian and coworkers connected benzylidene acetals of carbohydrates to Wang aldehyde resin. This linker was used as a temporary protecting group for... 

Quinazolines are of great interest in the pharmaceutical industry as protein tyrosine kinase inhibitors. Dener et al 8 described a synthesis starting from 2-methoxybenzaldehyde, Wang, or Rink resins. With the aldehyde resin reductive aminations were undertaken to yield polymer-bound secondary amines (Fig. 7). The latter were subjected to 2,4-dichloro-6,7-dimethoxyquinazoline to give the 4-amino-substituted derivatives. These were then allowed to react with primary or secondary amines at 135-140° in the presence of DBU in DMA. As a result of a detailed scope and limitation study, Dener et al,28 note that some bifunctional amines, such as piperazine, give to some extent dimeric derivatives. 

Chloromethyl resin Wang resin 2-Chlorotrityl resin Rink amide resin Hydroxymethyl resin Sasrin resin Sieber resin Aldehyde resin PAL amide resin TentaGel S NH2... 

Microwave irradiation has been used to accelerate the Gewald reaction for the one-pot synthesis of N-acyl aminothiophenes on solid support [67]. A suspension of cyanoacetic acid Wang resin 35, elemental sulfur, DBU and an aldehyde or ketone 36 in toluene was irradiated for 20 min at 120 °C in a single-mode microwave synthesizer (Scheme 13). Acyl chloride 37 was added, followed by DIPEA, and the mixture was irradiated for 10 min at 100 °C. After cooling to room temperature, the washed resin was treated with a TEA solution to give M-acylated thiophenes 38 in 81-99% yield and purities ranging from 46-99%. 

The solid-phase synthesis of the 2(lff)-pyrazinone scaffold is based on a Strecker reaction of commercially available Wang amide linker with appropriate aldehyde and tetramethylsilyl (TMS) cyanide, followed by cyclization of a-aminonitrile with oxalyl chloride resulting in the resin linked pyrazinones. This approach allows a wide diversity at the C-6-position of pyrazinone scaffold (Scheme 35, Table 1). As it has been shown for the solution phase, the sensitive imidoyl chloride moiety can easily undergo an addition/elimination reaction with in situ-generated sodium methoxide affording the resin-linked... 

In a dedicated combinatorial approach, Strohmeier and Kappe have reported the rapid parallel synthesis of polymer-bound enones [33]. This approach involved a two-step protocol utilizing initial high-speed acetoacetylation of Wang resin with a selection of common /i-ketoesters (Scheme 7.13) and subsequent microwave-mediated Knoevenagel condensations with a set of 13 different aldehydes (see Section 7.3.6). 

Intramolecular Dieckmann cyclization of polystyrene-bound pimelates has been used to prepare (l-keto esters (Entry 4, Table 3.41). Oxidative cleavage reactions leading to the formation of aldehydes include the ozonolysis of resin-bound alkenes, the periodate-mediated cleavage of 1,2-diols, and the oxidation of Wang resin derived ethers (Entries 5-7, Table 3.41). 

Polystyrene-bound allylsilanes react with /V-(alkoxycarbonyl)imincs under Lewis acid catalysis to yield /V-homoallylcarbamates (Entry 4, Table 14.9). Similarly, Wang resin bound carbamates have been successfully N-alkylated with allylsilanes and aldehydes in a Mannich-type reaction (Entry 5, Table 14.9). Resin-bound /V-(alkoxycarbo-nyl)imines can be generated either from unsubstituted carbamates ROCONH2 by... 

Notes. This test is very reliable. This test is compatible with acid-labile resins such as the Wang and chlorotrityl resins. While in the case of the Wang resin similar results were obtained, in the case of the chlorotrityl resin solutions also became colored, indicating cleavage of the aldehyde (BAL handle) from the resin. 

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