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(+)-Lentiginosine (14) and (7R)-7-hydroxylentiginosine (26), powerful inhibitors of amyloglucosidases, and their enantiomers were obtained in high overall yields by a multistep synthesis involving 1,3-dipolar cycloaddition of enantiopure tartaric acid derived pyrroline N-oxides. Structurally related (S,S)-3,4-dihydroxypyrrolidines 29-33 were synthesized as simpler models and tested towards 24 glycosidases.

Enantiopure five-membered ring nitrones derived from L-tartaric acid and from L-malic acid undergo highly regio- and stereoselective cycloaddition reactions with an excess of racemic 2,3-dihydro-l-phenyl-1H-phospholes producing two readily separable tricyclic cycloadducts and concomitantly effecting kinetic resolution of the dihydrophosphole derivative. Stereochemistry of the cycloaddition process and scope of the kinetic resolution process have been established in details and adjusted to produce dihydrophosphole derivatives in good yields and in very high optical purity. To effect syntheses of single cycloadducts of 100% ee the techniques of doubly asymmetric synthesis and parallel kinetic resolutions have been employed. The resulting tricyclic cycloadducts feature 2,2'-connection of pyrrolidine and phospholane rings and five to seven contiguous stereogenic centers of which three have been induced and one or two kinetically resolved during the cycloaddition process.

The stereochemistry of the major endo adduct obtained in the thermal Diels-Alder reaction of (S)-methylphenylvinylphosphine oxide and cyclopentadiene was analyzed by a single-crystal X-ray diffraction technique C14H17OP, space group P212121, a = 7.042(1) A, b = 10.522(1) A, c = 18.039(1) A, V = 1336.6(3) A Z = 4. The structure was solved by direct methods and was refined by full matrix least-square calculations to R = 0.043 and S = 1.033 using 2635 unique reflections with 1 > 3[sgrave](1). In the crystal packing two intermolecular C—H…O contacts involving phosphoryl oxygen and α and ortho hydrogens were revealed. The studied compound was identified as the endo adduct of the S configuration at C2. On the basis of this finding it could be concluded that (S)-methylphenylvinyl-phosphine oxide preferred to enter the studied 4 + 2 cycloaddition in the s-trans conformation.

The structure and absolute configuration of the predominant of the two diastereomeric 7, 8-di-tert-butoxy-1-phenyloctahydro-1H-pyrrolo[1, 2-b]phospholo[2, 3-d]isoxazole 1-sulfides obtained in the kinetic resolution experiment involving cycloaddition reaction of (S, S)-3, 4-di-tert-butoxy-3, 4-dihydro-2H-pyrrole 1-oxide (1) with an excess of racemic 2, 3-dihydro-1-phenyl-1H-phosphole 1-sulfide (2), was determined by a single-crystal X-ray diffraction technique. C22H34O3NPS, trigonal, space group P31, a = b = 11.831(1), c = 14.761(2) A, α = β = 90°, γ = 120°, V = 1789(4) A3 Z = 3. The structure was solved by direct methods and was refined by full matrix least-squares calculations to R = 0.031 and Rw = 0.036 using 3737 unique reflections with I > 3[sgrave](I). The absolute configuration of the studied molecule was determined by calculation of the ETA (η) parameter and was found to be 1S, 3aR, 7S, 8S, 8aR, 8bR. This finding assigns unequivocally the S configuration to the faster reacting enantiomer o...

The 1,3-dipolar cycloaddition of nitrones with chiral vinylphosphine oxides or sulfides provides 5-phosphinyl substituted isoxazolidines with selectivity up to 99:1. Use of chiral nitrones allows a more generalized stereoselective synthesis of these compounds, also by means of a double asymmetric induction. With a racemic phospholene oxide, the high diastereofacial selectivity of the cycloaddition gives rise to a single 4-phosphinyl substituted isoxazolidine from each enantiomer. Moreover, a certain degree of enantiomeric discrimination permits a partial kinetic resolution of the phospholene oxide.

The structure and absolute configuration of homochiral 2-benzyl-3-(2,2-dimethyl-1,3-dioxolan-4-yl)-4-phenylhexahydro-4H-phospholo-[2,3-d]isoxazole 4-oxide obtained in predominance from racemic 2,3-dihydro-1-phenyl-1H-phosphole 1-oxide and D-glyceraldehyde derived nitrone in the process of kinetic resolution was analyzed by a single-crystal X-ray diffraction technique. C23H28NO4P, monoclinic, space group P21, a = 5.7646(4) A, b = 8.7280(4) A, c = 21.3417(9) A, β = 92.828(5)°, V = 1072.464(5) A3, Z = 2. The structure was solved by direct methods and was refined by full matrix least-squares calculations to R = 0.034 and Rw = 0.041 using 2282 unique reflections with I > 3σ(I). The absolute configuration was determined by Hamilton method and was found to be 3S, 3aS, 4R, 6aS, 4′S. All the three five-membered rings in the studied molecule assumed a deformed envelope conformation and the planes of the two fused rings are found to form a dihedral angle of 59.3(1)°. One intramolecular and one intermolecula...

The simultaneous analysis of nuclear relaxation behaviour of 119Sn-1H and 117Sn-1H dipolar vectors from the proton spinlattice relaxation rates of the relative satellite peaks may yield a very accurate calculation of correlation times. The dipolar interaction between the proton and the bound tin nucleus is differently observed on the 119Sn and 117Sn satellite resonances in the 1H partially relaxed spectra. Provided that the internuclear proton - tin distance is known, from the difference of the relaxation rate of the lH-118Sn signal with those measured from its satellite peaks, the correlation time can be calculated from the two independent set of data.

The 1,3-dipolar cycloaddition of nitrones to vinyl phosphorus derivatives, mainly phosphines and their oxides and sulfides, has been studied. The cycloaddition to chiral racemic phosphine oxides and sulfides gives adducts with considerable diastereofacial selectivity. The transition state model for the cycloaddition is discussed.

The structure of the major product of the 1,3-dipolar cycloaddition of diphenylvinylphosphine oxide to C,N-diphenylnitrone was analyzed by a single-crystal X-ray diffraction technique. C27H24NO2P, monoclinic. space group P21c, a = 9.396 (1) A b = 22.057 (2) A c = 11. 171 (2) A V = 2244.9 (3)A and Z = 4. The structure was solved by direct methods and was refined by full matrix least-squares calculations to R = 0.040 and R w = 0.037 using 2905 unique reflections with 1 > 3σ(1). The studied molecule was identified as the 4-substituted regioisomer possessing C3-phenyl and diphenylphosphinyl substituents in the trans arrangement.

High-performance liquid chromatography utilizing chiral stationary phases (CSPs) is well established as a very simple and efficient method for obtaining discrete amounts of optically active compounds with high e.e., as well as for determining their enantiomeric composition We wish to demonstrate in the present work that a totally synthetic brush-type π-acidic CSP based on a bis(N,N′-3,5-dinitrobenzoyl) derivative of (R,R)- or (S,S)-trans-1,2-diaminocyclohexane as selector can be used successfully to resolve variety of chiral organophosphorus compounds containing stereogenic centers at phosphorus

Enantiopure five-membered ring nitrones derived from L-tartaric acid and from L-malic acid undergo highly regio- and stereoselective cycloaddition reactions with an excess of racemic 2,3-dihydro-1-phenyl-1H-phospholes producing two readily separable tricyclic cycloadducts and concomitantly effecting kinetic resolution of the dihydrophosphole derivative (diastereomeric ratio up to 10:l; stereoselectivity factor s = kS/kR = 14). The tricyclic cycloadducts feature 2,2′-connection of pyrrolidine and phospholane rings and five to seven contiguous stereogenic centers of which three are induced and one or two are kinetically resolved during the cycloaddition process.

In 1,3-dipolar cycloaddition of C,N-diphenylnitrone to diphenylvinylphosphine oxide (and also to diphenylvinylphosphine sulphide) the 4-substituted phosphinyl isoxazolidine is formed predominantly but in case of a cyclic nitrone the 5-substituted regioisomer prevails. Regiochemical distinctions between the isomeric phosphinyl isoxazolidines are best executed by means of 13C NMR spectroscopy.