Convertible Armstrong

Converted and interpolated from Angus, S., B. Armstrong, et al.. International Theimodynamic Tables of the Fluid State—7, Propylene, Pergamon, Oxford, 1980... 

Enzyme Reference Serums. Several companies sell lyophilized or stabilized reference serums for the calibration of instruments and for quality control. The label values given for the enzymatic activity of these serums should never be taken at face value, as at times they may be quite erroneous (19,33). Also, these values should only be used for the assay with which they were standardized, as interconversion of activity from one method to another for the same enzyme may often lead to marked errors. For instance, it is not recommended that alkaline phosphatase expressed in Bodansky units be multiplied by a factor to convert it to the units of the Ring-Armstrong method, or any other method for that matter. 

The oxidation of carotenes results in the formation of a diverse array of xanthophylls (Fig. 13.7). Zeaxanthin is synthesised from P-carotene by the hydroxylation of C-3 and C-3 of the P-rings via the mono-hydroxylated intermediate P-cryptoxanthin, a process requiring molecular oxygen in a mixed-function oxidase reaction. The gene encoding P-carotene hydroxylase (crtZ) has been cloned from a number of non-photosynthetic prokaryotes (reviewed by Armstrong, 1994) and from Arabidopsis (Sun et al, 1996). Zeaxanthin is converted to violaxanthin by zeaxanthin epoxidase which epoxidises both P-rings of zeaxanthin at the 5,6 positions (Fig. 13.7). The... 

Such a strategy follows the philosophy of resin capture, as introduced by Armstrong and Keating Keating TA, Armstrong RW. Postcondensation modifications of Ugi four-component condensation products 1-isocyano-cyclohexane as a convertible isocyanide. Mechanism of conversion, synthesis of diverse structures, and demonstration of resin capture. J Am Chem Soc 1996 118 2574-2583. See also Brown SD, Armstrong RW. Synthesis of tetrasubstituted ethylenes on solid support via resin capture. J Am Chem Soc 1996 118 6331-6332. 

Benzodiazepinediones 15 have been synthesized starting from anthranilic derivatives 13 and Armstrong convertible isocyanides 1. When the amino group of 13 is secondary, it does not interfere too much with the Ugi reaction, and the acid... 

Keating TA, Armstrong RW (1995) Molecular diversity via a convertible isocyanide in the Ugi four-component condensation. J Am Chem Soc 117 7842-7843... 

Hulme C, Peng J, Tang S-Y, Bums CJ, Morize I, Labaudiniere R (1998) Improved procedure for the solution phase preparation of 1, 4-benzodiazepine-2, 5-dione libraries via Armstrong s convertible isonitrile and the Ugi reaction. J Org Chem 63 8021-8023... 

Hulme C, Morrissette MM, Volz FA, Bums CJ (1998) The solution phase synthesis of diketopiperazine libraries via the Ugi reaction novel application of Armstrong s convertible isonitrile. Tetrahedron Lett 39(10) 1113-1116... 

One of the pioneer works in the synthesis of DKPs through MCRs was reported by Hulme and coworkers in a three-step solution phase protocol based on UDC [33, 34]. They have obtained a series of different DKPs by reacting Armstrong s convertible isocyanide with aldehydes, M-Boc-protected amino acids as bifunctional acid component containing a protected internal amino nucleophile, and amines in methanol at room temperature. After Ugi-reaction, the isonitrile-derived amide is activated with acid (UAC) and allows cyclization to the DKP with the... 

Krasavin et al. described the synthesis of dihydropyrazol pyrazine diones via Ugi-4CR, employing ferf-butyl isocyanide as a convertible reagent [102], The authors reported that, under microwave irradiation, the ferf-butyl isocyanide behaves similar to Armstrong s isocyanide, furnishing the DKPs in good yields. It is noteworthy that the low priced isonitrile applied may be helpful for developing large-scale syntheses in the future (Scheme 6). 

In addition to the synthetic route shown in Scheme 32, Armstrong approached the synthesis from the other direction, by converting the initial resin-bound iodide to a supported pinacolatoboronate 30 under platinum catalysis (Scheme 33). This was then coupled in the usual way with a solution-phase aryl iodide in high yield, and with much more satisfactory results than were obtained with the vinylboronates 29. This chemistry was later shown to be useful in solution for one-pot biaryl synthesis by genera-... 

Keating, T. A. Armstrong, R. W. Postcondensation Modifications of Ugi 4-Component Condensation Products—1-Isocyanocyclohexane as a Convertible lsocyanide—Mechanism of Conversion, Synthesis of Diverse Structures, and Demonstration of Resin Capture, J. Am. Chem. Soc. 1996, 118, 2574-2583. 

Camphorsulfonyl)imine has been reported as a by-product of reactions involving the camphorsulfonamide.2 5 Reychler in 1898 isolated two isomeric camphorsulfonamides,2 one of which was shown to be the (camphorsulfonyl)imine by Armstrong and Lowry in 1902.3 Vandewalle, Van der Eycken, Oppolzer and Vullioud described the preparation of (camphorsulfonyl)imine in 74% overall yield from 0.42 mol of the camphorsulfonyl chloride.6 The advantage of the procedure described here is that, by using ammonium hydroxide, the camphorsulfonyl chloride is converted to the sulfonamide in >95% yield.7 The sulfonamide is of sufficient purity that it can be used directly in the cyclization step, which, under acidic conditions is quantitative in less than 4 hr. These modifications result in production of the (camphorsulfonyl)imine in 86% overall yield from the sulfonyl chloride. 

Cyclohexen-l-yl isocyanide 1 known as Armstrong convertible isocyanide has also been called universal isocyanide . It was prepared in 1963 by Ugi and Rose-ndahl [5] to be used as a synthetic equivalent of the unknown hydrogen isocyanide . The Ugi-4CR between 1, cyclohexanone N-benzylimine 2, and formic acid afforded N-cyclohexen-l-yl amide 3, which was cleaved in acidic medium to afford the primary a-acylamino amide 4 rather than the N-substituted amides usually obtained by the Ugi-4CR (Scheme 2.1). 

The Hulme group has reported two three-step, one-pot solution-phase procedures for the preparation of 2,5-diketopiperazines, based on the UDC strategy. The first method [74a] used ethyl glyoxylate as a bifunctional carbonyl input in an Ugi-4CR with amines, isocyanides, and N-Boc a-amino acids that afforded adducts 121, which were N-deprotected and cyclized to the desired products 122 (Scheme 2.44). The second method [8c] used Armstrong s convertible isocyanide 1 in a reaction with N-Boc a-amino acids, aldehydes, and amines that afforded products 123, which were deprotected and cyclized to diketopiperazines 124 (Scheme 2.44). 

An elegant two-step synthesis of l,4-benzodiazepine-2,5-diones was reported by Keating and Armstrong [84], Products 148 arising from the Ugi-4CR reaction between anthranilic acids, 1-isocyano-l-cyclohexene 1, aldehydes, and amines were converted into l,4-benzodiazepine-2,5-diones 149 on treatment with methanolic HC1 (Scheme 2.54). 

The selected examples by Keating and Armstrong [59, 60] reported the synthesis of a small discrete solution library (eight compounds) of Ugi 4CC products and their further elaboration. The concerted mechanism of the Ugi 4CC is shown in Figure 7.5. The scarcity of commercial isocyanides encouraged the use of a convertible isocyanide [59, 60], which allowed its postcondensation transformations in other functional groups, which are shown in Figure 7.6. 

The suffrage movement was an active issue at Armstrong College. In 1906, a very heated debate among the women students resulted in a vote of 29 in favour of women s suffrage and 55 against.12 As the author of the report noted Some of the suffragettes did not look very happy when the result was announced, however, several converts to the cause were made. 12... 

Packer M, Poole-Whson PA, Armstrong PW, Cleland JG, Horowitz JD, Massie BM, Ryden L, Thygesen K, Uretsky BF. Comparative effects of low and high doses of the angiotensin-converting enzyme inhibitor, lisinopril, on morbidity and mortality in chronic heart failure. ATLAS Study Group. Circulation 1999 100(23) 2312-18. 

Massie BM, Armstrong PW, Qeland JG, Horowitz JD, Packer M, Poole-Wilson PA, Ryden L. Toleration of high doses of angiotensin-converting enzj me inhibitors in patients with chronic heart faUnre resnlts from the ATLAS trial. The Assessment of Treatment with Lisinopril and Survival Arch Intern Med 2001 161(2) 165-71. 

Figure 3-11 four-component Ugi reaction reported by Keating and Armstrong. A combinatorial mixture of the intermediate cyclohexenyl amide can be split into several portions, and each can be further reacted to give a variety of products, all of which will be combinatorial. (Reaction redrawn from description from Keating. T. A., and Armstrong. R. W Molecular diversity via a convertible isocyanide in the Ugi four-component condensation J. Am. Chem. Soc. 117 7842-7843. 1995.)... 

---