Supplementary Materialsao0c01064_si_001. providing 1,4-adducts, five-membered band 1,2-azaphospholenes.14 Streubel et al. used 1,2-addition to a C=N bond, resulting in the formation of the azaphosphiridine complex from the thermal decomposition of the 2= 2, 3, 4], giving bicyclic (CH2)bridged diazaphospholanes.17 The chemistry of 2,4-bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide (Woollins reagent, WR) has been developed and exploited widely by us and other groups as a versatile selenation reagent or synthetic precursor in synthetic chemistry.18?31 Recently, we have reported that Woollins reagent can add to the C=N bond of a series of conjugated Schiff bases to generate a series of stable five-membered phosphorusCseleniumCnitrogen heterocycles.32 In continuation of our interest in the chemistry of WR toward various organic substrates, we report herein the reactivity of WR toward amido-Schiff bases, which led to the formation of a series of five- and six-membered PCSe heterocycles and their related X-ray structures. To the best of our knowledge, this is the first reported synthesis and single-crystal structures of such small ring phosphorusCselenium heterocycles incorporating single SeCP=Se or NCP=Se linkage. Results and Discussion The selenation of N-substituted benzylidenebenzohydrazides 1 and 2 by WR afforded new six-membered phosphorusCselenium heterocycles 3 and 4 in 56 and 46% yield, respectively (Scheme 1). It can be suggested that the formation of heterocycles 3 and 4 results from the addition of an equilibrium monomeric species PhPSe2,33 arising from WR into the C=N bond of the unsaturated Schiff bases 1 and 2 to generate an unstable intermediate I, the second option can perform an intermolecular coupling response II to provide the final items heterocycles 3 and 4 by additional lack of two substances of benzaldehyde and two substances of N2. The 31P NMR spectra of heterocycles 3 and 4 display wide singlets at 45.6 and 46.4 ppm, respectively, flanked by selenium satellites with 31PC77Se coupling constants of 380/373 and 752/759 Hz; as well as the 77Se NMR spectra screen dual doublets at 461.4/338.7 and ?215.2/C213.0 ppm using the matching coupling constants, indicating the current presence of solitary PCSe bonds and increase P=Se bonds in both substances. Open up in another window Structure 1 Synthesis from the Six-Membered PhosphorusCSelenium Heterocycles 3 and 4 Oddly enough, under identical response condition, benzohydrazide 5 reacts with WR towards the provide five-membered 2-(benzo[ em d /em ][1,3]dioxol-5-yl)-5-( em p /em -tolyl)-1,3,4-selenadiazole 7 in 55% produce alongside the anticipated six-membered phosphorusCselenium heterocycle 6 in 14% produce (Structure 2). The same response mechanism (Structure 1) may be used to rationalize the forming of 6, and we’ve reported that result of 1 previously,2-diacylhydrazines or carbohydrides with WR leads to symmetrical 2,5-disubstituted 1,3,4-selenadiazoles,20,29 and the forming of 6 isn’t unexpected consequently, following a identical path. Two diastereomers in ca. 1:1 strength ratio had been determined in the 31P NMR spectral range of chemical substance 6, which ultimately shows two wide singlet indicators along with coordinating selenium satellites as within substances 3 and 4. The 77Se SGX-523 inhibition NMR SGX-523 inhibition for selenium-containing heterocycle 7 shows a singlet peak at 769.0 ppm, which is in keeping with its analogues.20,29 Open up in another window Structure 2 Formation from the Heterocyclic Substances 6 and 7 However, as opposed to the above mentioned results, the result of WR with conjugated amido-Schiff bases 8aCd beneath the similar conditions resulted in some unexpected fused phosphorusCseleniumCnitrogen heterocycles 9aCd in good yields (50C61%), as demonstrated in Structure 3. The response mechanism isn’t clear; we are able to surmise that the forming of these fused heterocycles could be via selenation/cyclization/cycloaddition, but whether this occurred concurrently or successively can be unfamiliar. The 31P NMR spectra of these fused heterocycles 9aCd show only singlets at 65.2C78.8 ppm, with the corresponding selenium satellites ranging from 816 to 822 Hz. One doublet and one singlet were observed in the 77Se NMR spectrum for each compound. Open in a separate window Scheme 3 Preparation of the Fused Five-Membered Rings 9aCd Another interesting result is usually from the reaction of WR with 4-methyl- em N /em -(2-methyl-3-phenylallylidene)benzohydrazide 10, which led to a five-membered phosphorusCselenium heterocycle 11 in 55% yield (Scheme 4) rather than the fused compounds as Rabbit Polyclonal to p15 INK shown in Scheme 3. The formation of this compound might first proceed by a [3 + 2] cycloaddition of the Schiff base with a reactive species PhPSe233 from WR to give an intermediate III, which is usually then reduced to deliver an intermediate IV, in which the C=C and C=O groups SGX-523 inhibition are further reduced to the corresponding saturated sp3 CCC and CH(OH).