Combinatorial Chemistry with Laser Optical Encoding

Abstract

COMMUNICATIONSall-E content characteristic of the double elimination process holds for the present case as well: all-E:9Z:[(lIZ) + (13Z)l = 91 :4:5.We compared this new process with those used commerciall~.[~] The Hoffmann-La-Roche process involves a C,, + C, route, and BASF makes use of the Wittig reaction between C,, and C, building blocks. Rh6ne-Poulenc also employs the C,, + C, combination based on the Julia sulfone coupling. Our strategy is novel in that two C , , components are coupled. The C,, skeletons are one of the most common units in terpenoid derivatives and, accordingly, readily available. As a whole, our process has the twofold benefit of ready availability of the starting materials and simple operation.[61 We have shown that the following reactions can be integrated: a) addition of carbanion to carbonyl, b) 0-alkylation of the addition product, and c) successive elimination of the alkoxy and sulfinyl groups. The only modification of the stepwise process is made for the 0-alkylation. This results in not only compaction of the process but increase in the total yield. Although we took up a rather simple case in this study, it has proved that even a slight modification can bring about critical improvements of the chemical process. This suggests the importance and potential of the integrated chemical process for designing a synthesis. Experimental SectionNaI (225 mg. 1.5 mmol), cyclogeranyl sulfone 1 [3c] (362 mg, 1.3 mmol), and T H F (2 mL, dried over sodium benzophenoneketyl) were placed in a flame-dried, twonecked flask. A solution of BuLi in hexane (1.6 M, 0.75 mL, 1.2 mmol) was added, and the mixture stirred at -78 "C (dry ice/MeOH) under argon for 1 h. After thc addition of aldehyde 2 [3c] (211 mg, 1.0 mmol) in T H F (1 mL) followed by MOMCI (0.09 mL, 1.2 mmol), the solution was stirred for 4 h at -78°C and 1 h at room temperature. Cyclohexane (3 mL) and KOMe (701 mg, 10 mmol) were added, and the mixture stirred for 1 h at room temperature and 1 h at 40°C. The reaction was quenched with aqueous NaHCO, solution (10 mL) and ethyl acetate (15 mL). After separation of the organic layer and extraction of the aqueous phase with ethyl acetate (2 x 15 mL), the combined organic fractions were washed with brine (20 mL), dried over MgSO,, and concentrated under reduced pressure (crude, 452 mg). Hexane ( 5 mL), pyridine (0.5 mL), acetic anhydride (2 mL), and DMAP (48 mg, 0.4 mmol) were added to the crude product under argon, and the mixture stirred for 1 h at room temperature. Aqueous NaHCO, solution (20 mL) and ethyl acetate (15 mL) were added at 0"C, and the organic layer separated. The aqueous phase was extracted with ethyl acetate (2 x 15 mL), and the combined organic fractions washed with brine (20 mL), dried over MgSO, and concentrated under reduced pressure (crude, 504 mg). The crude oil was analyzed by HPLC; 76% yield, 248 mg, all-E:9Z:[(llZ) + (13Z)l = 91:4:5 (column: ZORBAX SIL 4.6mmx 25 cm; eluent: terr-butylmethyl ether/hexane 51100; internal standard: 2,6-xylenol).

Practical Aspects of Combinatorial Solid‐Phase Synthesis

“…80,81 Later, various tags that give a unique identifier to an individual bead, allowing deconvolution of the compounds structure, were developed and reported. 26,28,[82][83][84][85][86][87][88] The tags are generally cleaved from the resin using an orthogonal cleavage method, similar to that used to detach the screening compound from the bead. Coding subunits are those that can be easily identified by well-established analytical microtechniques: amino acids (Edman degradation and HPLC), 89,90 electrophoretic tags (halocarbon molecules determined after silylation by gas chromatography), 91,92 or amines.…”

Combinatorial/Library Peptide Synthesis

“…Radiofrequency tags or barcodes allow for automating the sorting process [103,104]. Exciting technologies can be designed using barcodes miniaturized to a level that each particle of the solid support has its own barcode [105][106][107][108][109]; unfortunately, at this level of miniaturization, the cost of the individual particles and the need for specialized equipment used for their reading may be prohibitive for widespread application.…”

Solid-phase combinatorial synthesis using MicroKan reactors, Rf tagging, and directed sorting

“…Three technological innovations are essential for the success of the system: (1) application of microreactors as the reaction units in solid-phase synthesis; (2) use of radiofrequency tagging as the tracking method; 8,9 and, (3) development of the directed sorting technology for split & pool. 10 The integrated system has been successfully applied in the generation of compound libraries by both ourselves and researchers from other pharmaceutical and academic organizations. This article describes the basic features and components of the system and also illustrates its application in chemistry with a number of library syntheses.…”