Kaiser oxime resin

Depending on the reaction temperature and reaction time, tetrahydroisoquinoline 357 afforded different mixtures of 1,2,3,4,11,11 a-hcxahydro-6//-pyrazino[ 1,2-3]isoquinolines 358-361 and tetracyclic compound 362 (Scheme 30) <2005JA16796>. Each of the individual diastereoisomers 358-361 could be transformed into the compound 362. z7r-3//,4a//-3-Phcnylpcrhydropyra/ino[ 1,2-7]isoquinoline-l,4-dione was prepared via automated parallel solid-phase synthesis on Kaiser oxime resin <1998BML2369>. l,2,3,5,6,7-Hexahydropyrido[l,2,3-r/f ]quinoxaline-2,5-dionc was obtained by catalytic hydrogenation of ethyl 3-(2-oxo-l,2,3,4-tetrahydro-5-quinoxalinyl)acrylate in the presence of TsOH over 5% Pd/C catalyst under 40 psi of hydrogen <1996JME4654>. 

JC Hendrix, JT Jarrett, ST Anisfield, PT Lansbury. Studies related to a convergent fragment-coupling approach to peptide synthesis using the Kaiser oxime resin. J Org Chem 57, 3414, 1992. 

Scheme 11 Synthesis of a Lanthionine Peptide via Solid-Phase Peptide Synthesis and Final Cleavage from Kaiser Oxime Resin 481...

A high yielding synthesis of anthranil from 2-nitrobenZaldehyde makes use of zinc and allyl bromide as the reducing agent. The method has also been used for the preparation of 3-substituted anthranils from 2-nitrophenyl ketones <99H(51)1921>. A solid phase synthesis of 3-aminobenzisoxazoles 15 is based on the displacement of fluoride from 2-fluorobenzonitriles by the Kaiser oxime resin and subsequent hydrolysis of the C=N bond <99JOC4547>. A synthesis of 3-(2-dialkylaminoethyl)benzisoxazoles from oximes of 2-hydroxyphenyl ketones has also been described <99H(51)2139>. ... 

Strategies that lead to the formation of isoxazoles during cleavage from an insoluble support include the oxidative cleavage of /V-(4-alkoxybenzyl)isoxazolidincs with DDQ to yield isoxazolines (Entry 14, Table 15.16), the nucleophilic cleavage of 2-acyl enamines with hydroxylamine (Entry 15, Table 15.16), and the acidolysis of 2-cyano-phenols etherified with an oxime resin (Entry 17, Table 15.16). The required oxime ethers for the latter synthesis were prepared by reaction of the corresponding 2-fluorobenzonitriles with Kaiser oxime resin [203],... 

Kaiser oxime resin cross-linked polystyrene with 4-nitrobenzophenone oxime linker Lawesson s reagent 2,4-bis(4-methoxyphenyl)-l, 3-dithia-2,4-diphosphetane-2,4-disulfide... 

Scheme 1. The Kaiser-oxim resin 1 is permanently activated and can be cleaved by nucleophiles. Kenners sulfonamide resin 2 is stable against acids and bases but rendered labile against nucleophilic attack after conversion to the tertiary amide 3.

The azide procedure adopted for the synthesis of apamin by CSPPS included the preparation of 4- [4-(bromomethyl)-3-nitrobenzoyl]amino)(phenyl)methylphenyl-copo-ly(styrene-l%-divinylbenzene) (BrCH2-Nbb-resin) 1 which was used for the generation of the protected hydrazide peptide (Scheme 1). The Kaiser oxime resin can also be used for generation of hydrazide peptides. 

Selective urea formation on the Kaiser oxime resin without cleavage is only possible at room temperature. At elevated temperature cleavage is observed. 

Chloromethyl resin Wang resin 2-Chlorotrityl resin Rink amide resin Kaiser oxime resin TentaGel S RAM... 

Cleavage, nonstandard Aminomethyl resin Chloromethyl resin Benzoic acid resin Hydroxymethyl resin Rink amide resin Wang resin PAL amide resin MBHA resin Kaiser oxime resin REM resin TentaGel S OH TentaGel S PHB Spheron Ara 1000 ... 

The traditional method for generation of protected peptide fragments in concert with the Boc-benzyl strategy is saponification or transesterification to cleave the PAM anchor. However, such methods are used less often today because of certain incompatibilities, as well as the development of more efficient techniques [95]. Allyl, o-nitrobenzyl, phenacyl (also cleaved by photolysis) [109,110], and fluorenylmethyl (cleaved by secondary amines) [111-113] handles all offer orthogonal mechanisms of release. The Kaiser oxime-resin is also popular for the production of protected segments it is cleaved via aminolysis with an amino acid ester or transesterification with hydroxypiperidine (reduction of this ester provides the free carboxyl) [97,114]. 

The main problem associated with use of Kaiser oxime resin is its lability to nucleophiles. Loss of peptide from the resin can be provoked by the free V -amino group of the growing peptide chain on neutralization with base, after acidolytic removal of the V -Boc group. Chain elongation on this... 

Kaiser oxime resin, 4-nitrobenzophenone oxime resin, a base-labile resin widdy used for the synthesis of Boc/Bzl-protected segments. Several methods have been de-... 

Alacid, E. and Ndjera, C. (2006) PaUadated Kaiser oxime resin as precatalyst for the Heck reaction in organic and aqueous media. Synlett, 2959-64. 

As conclusion, the high catalytic efficiency of the polymeric palladacycle derived from Kaiser oxime resin similar to that of related unsupported dimeric pal-ladacycles was observed in the Mizoroki-Heck reaction. This polymer showed a good catalytic activity, not only in organic but also in aqueous media, for aryl iodides, bromides, and activated chlorides with high turnover numbers (TONs), rmder aerobic conditions at relatively lower temperature. 

Starting from Kaiser oxime resin 408, 5 equiv of Boc-amino acid 409 and 5 equiv of Die in DCM or DMF for 16 h completed the first coupling (Scheme 9.48). Resin 410 was treated with 25% TFA in DCM for 30 min, then 5 equiv of Boc-amino acid 411 and 5 equiv of both Die and DIEA in DCM (or DMF) for 4h generated dipeptide 412. After another deprotection using 25% TFA in DCM, the subsequent resin-bound dipeptide was treated with 2.2 equiv of DIEA and 5 equiv of acetic acid in DCM for 16 h to induce the intramolecular coupling, resulting in the cyclocleavage product 413. 

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