ArgoGel resin

Scheme 1.1 Attachment of a pyridyl ligand and (1) to ArgoGel resin (2).

Fig. 10. 400 MHz H HRMAS NMR spectra of ArgoGel resin swollen with 92% CDCl3/8% CD3OD. The macrocycle, stylized as a ring, reversibly threads onto the polyethyleneglycol chain in a scheme depicted on the left. This is evident in the spectra to the right, where the upper unsplit spectrum was obtained in the absence of the macrocycle, and the lower was obtained after addition of the macrocycle. Reproduced with permission from Ref. 102. Copyright 2001 Wiley-YCH.

The carbazate linker 1.12 (69), obtained from hydroxy Argogel resin activated with CDI and reacted with anhydrous hydrazine, was used to support ketone-based protease inhibitors and to release them after SPS using TFA/H2O/CH3CHO/TFE 1/4/4/15 in 4 h at rt. 

A more recent approach to safety-catch cleavage of resin-bound amides (PS or ArgoGel resin) to their secondary amides 142 was pubUshed by Sci-cinski et al. in 2004 (Scheme 21) using an indole hnker [176]. 

A combination of a multicomponent Ugi transformation and an intramolecular Diels-Alder reaction has been developed by Paulvannan [13]. Hence, condensation of the resin-bound (acid-labile ArgoGel-Rink resin) amine 10-37 with a tenfold... 

ArgoGel-MB-CHO resin (366 mg, 0.42mmol/g substitution) was placed into an Ace pressure tube (note 5). Trimethyl orthoformate (TMOF 5 mL) was added to the flask along with the primary amine (10 equiv.). The tube was capped and heated for 2h at 70°C in a rotating oven (note 6), and cooled. The TMOF solution was removed with the use of a filtration cannula, and the entire process was repeated. The resin was washed with TMOF (5 mL, lx) and anhydrous methanol (5 mL, 3 x) Anhydrous methanol (5 mL) was added to the resin, followed by the addition of sodium borohydride (133 mg, 20 equiv.). After vigorous gas evolution had ceased, the tube was capped and agitated for 8 h at room temperature. The resin was then transferred to a polypropylene reaction vessel and washed with methanol (5mL, 3 x), methanol water (1 1, 5mL, 3 x), DMF water (1 1, 5mL, 3 x), DMF (5mL, 3 x), and methylene chloride (5 mL, 3 x). 

ArgoGel MB-CHO resin was purchased from Argonaut Technologies, substitution = 0.42 mmol/g, lot 104—20. 

Cleavage of the thiazoles from ArgoGel MB-CHO resin required longer cleavage times (4h) and modest heating... 

In this scheme, Fmoc -/ -alanine is coupled to ArgoGel-Wang resin using standard methodology to give resin 1, and then the Fmoc group is... 

Figure 1.3 Structure of monofunctional hybrid PEG-PS resins (Tentagel, left) and of bifuno-tional hybrid PEG-PS resins (Argogel, right).

Figure 1.22 MAS-HR H-NMR spectrum of A-Fmoc-6-amino hexanoic acid linked via amino photolinker to Argogel AG-PS resin.

A recent review by Porco et al. (171) highlighted the use of an automated SP chemistry development workstation (172) for the rapid optimization of SP reaction conditions in an automated parallel manner. Two examples will be described here first, the influence of temperature on the generation of ureas from an oxime resin and, second, optimization of the length of time of reaction of the Suzuki biaryl coupling on an Argogel-Rink resin. 

The reaction of an a-haloketone with thiourea gives rise to the 2-aminothiazole. This reaction has been used in a combinatorial approach for the synthesis of libraries of 2-aminothiazoles in excellent yields and purities first in the solution phase <1996BML1409> and then on a solid support using Rink amide MBHA, glycyl-Rink amide MBHA, and reductively aminated ArgoGel MB-CHO resins (Scheme 55) <1998JOG196>. 

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