A new synthesis of .beta.-keto phosphonates and .beta.-keto silanes

All reagents were purchased from Sigma-Aldrich (St Louis, MO, USA) or Macrocyclics (Dallas, TX, USA) unless stated otherwise. Solvents were freshly distilled on appropriate driers and reactions run under an inert Argon atmosphere (CH 2 Cl 2 was distilled over P 2 O 5 , THF was distilled over sodium). All compounds apart from those containing Gd were fully characterized by 1 H (400 Hz) NMR, 13 C (400 Hz) (Bruker AMX-400 spectrometer) and the final products with Gd were characterized by mass spectrometry (EIMS and HRMS). Chemical shifts are expressed in δ ppm. All photophysical experiments were carried out using spectroscopic-grade solvents. Column chromatography was performed either over Silica Gel 60 (70-230 mesh) or neutral Alumina (Brockmann grade III, 50 mesh). UV-visible spectra were recorded on Varian Cary 50 Bio UV-visible spectrophotometer using CH 2 Cl 2 as solvent unless otherwise specified. Fluorescence spectra were recorded on a Varian Cary Eclipse fluorescence spectrophotometer with an excitation wavelength in the "Soret" band region between 410 and 425 nm.

The Journal of Organic Chemistry, 1975

8 i + H30' were chosen and an attempt was made to synthesize the diperoxides under essentially the same conditions. The results are shown in . No attempt was made to maximize the yields of any but the first entry in .

ChemInform, 2005

C NMR spectra were measured with JEOL Delta-500 (125 MHz) spectrometer in CDCl 3 with reference to the CDCl 3 triplet ( 77.2) or in C 6 D 6 with reference to C 6 H 6 triplet ( 128.0). Resonance patterns were described as s = singlet, d = doublet, t = triplet, m = multiplet, and br = broad. The assignment of 1 H and 13 C NMR spectra is based on H-H decoupling and HMQC experiments. Low-and high-resolution mass spectra (EI-MS) were obtained with a JEOL JMS-SX102 spectrometers. For routine chromatography, the following adsorbents were used: Kanto Kagaku silica gel 60N for column chromatography; Merck precoated silica gel 60 F-254 plates for analytical thin-layer chromatography. All moisture sensitive reactions were performed under a positive pressure of nitrogen. Anhydrous MgSO 4 was used for drying all organic solvent extracts in workup, and the removal of the solvents was performed with a rotary evaporator. Dry solvents and reagents were obtained by using standard procedures. To a cooled (-80 °C) solution of 1 (100 mg, 0.507 mmol), 7 (73 µL, 0.608 mmol), and HMPA (0.353 mL, 2.03 mmol) in THF (1.72 mL) was added NHMDS (0.91 M in THF, 1.23 mL, 1.12 mmol). The reaction mixture was stirred at the same temperature for 80 min before addition of saturated aqueous NH 4 Cl 4 solution (10 mL), and extracted with Et 2 O (5 mL x 3). Combined organic phases were washed with saturated brine (10 mL), dried, and concentrated. The residue was subjected to column chromatography (basic alumina, 5 g, elution with hexane:AcOEt = 10:1) to give 8 (106 mg, 83%).

Chemische Berichte, 1991

Epoxidation / Dioxiranes / Enol silyl ethers / Enol phosphates / Enol esters and lactones / Caroate The epoxides 2a -u (Table ) of the enol silyl ethers 1 a, b, enol phosphates 1 ck, and enol esters and lactones 11 -u were prepared in excellent yields by epoxidation with isolated dimethyldioxirane (4) (as acetone solution). These labile epoxides (stable below 0°C) could be isolated in pure form and characterized spectroscopically (IR, *H and I3C NMR). The de-rivatives 2pu were sufficiently stable so that even C,H analyses were obtained. Warming up to room temperature led to rearrangement to the corresponding a-oxy-functionalized car-bony1 products 3. Since epoxide 2c was sufficiently resistant towards hydrolysis, it could be prepared by the in situ method. Ketone 3f2? 183 mg (86%), colorless liquid, obtained from 213 mg (0.87 mmol) of 2f. -'H NMR (250 MHz, CDCI,): 6 = (m, 3H), 7.56-7.67 (m, 2H). -"C NMR (63 MHz, CDC13): 6 = (arom.), 128.8 (arom.), 133.6 (arom.), 134.4 (arom.), 192.3 (d, Jc,p = Ketone 3g27): 146 mg (83%), colorless liquid, obtained from 176 mg (0.65 mmol) of 2g. -'H NMR (250 MHz, CDCI3): 6 = 0.98-1.16 (m, 6H), 4.00-4.12 (m, 4H), 5.12 (d,

J Org Chem, 1970

Journal of Organometallic Chemistry, 2003

1-Sila-2,4-cyclopentadienes (siloles) bearing five organyl groups and a diethylboryl group in 3-position (3), four organyl groups, a trimethylstannyl and a diethylboryl group in 2,4-positions (4), four organyl groups, a diethylboryl group in 3-position and a hydrido function at the silicon atom (5) react by [4'/2]cycloaddition with dimethyl acetylenedicarboxylate, MeOC(O) Ã/CÅ/CÃ/C(O)OMe (1), and tetracycanoethylene, (NC) 2 CÄ/C(CN) 2 (2), to give 7-silanorbornadienes (6 Á/8) and 7-silanorbornenes (10 Á/12), respectively. The silole 5 is converted into isomers 8 and 8?, and 12 and 12?, in which the SiMe group in each major isomer (8 and 12) occupies the synposition with respect to the C(2) Ä/C(3) bond. The molecular structure of 10a was determined by X-ray analysis. The 7silanorbornadiene (7) rearranges into a benzene derivative by formation of an Si Ã/O bond and 1,3-migration of the trimethylstannyl group. All products were characterised in solution by multinuclear magnetic resonance ( 1 H-, 11 B-, 13 C-, 29 Si-, 119 Sn-NMR spectroscopy). The geometries of 1,4,7,7-tetramethyl-7-silanorbornadiene, -7-silanobornene, and -7-silanorbornane were optimised by ab initio MO calculations (RHF/6-311'/G(d,p) and chemical shifts d 29 Si were calculated (GIAO-RHF/6-311'/G(d,p)). #

Journal of Mass Spectrometry, 1998

Helvetica Chimica Acta, 1984

The Journal of Organic Chemistry, 1979

Org. Biomol. Chem., 2016

Nuclear magnetic resonance [ 1 H NMR (500 MHz), 13 C NMR (125 MHz)] spectra were determined on JEOL ECA-500 instrument. Chemical shifts for 1 H NMR were reported in parts per million downfields from tetramethylsilane (δ) as the internal standard and coupling constants were in hertz (Hz). The following abbreviations are used for spin multiplicity: s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet, br = broad. Chemical shifts for 13 C NMR were reported in ppm relative to the centerline of a triplet at 77.0 ppm for deuteriochloroform. High-resolution mass spectra (HRMS) were obtained on a BRUKER DALTONICS micrOTOF (ESI). Infrared (IR) spectra were recorded on a SHIMADZU IRPrestige-21. Optical rotations were measured on a JASCO P-1030 Polarimeter at RT using the sodium D line. Analytical thin layer chromatography (TLC) was performed on Merck precoated analytical plates, 0.25 mm thick, silica gel 60 F 254. Preparative TLC separations were made on 7 x 20 cm plates prepared with a 0.25 mm layer of Merck silica gel 60 F 254. Compounds were eluted from the adsorbent with 10% methanol in chloroform. Column chromatography separations were performed on KANTO CHEMICAL Silica Gel 60 (spherical) 40-50 µm, Silica Gel 60 (spherical) 63-210 µm or Silica Gel 60 N (spherical, neutral) 63-210 µm. Reagents and solvents were commercial grades and were used as supplied with the following exceptions. 1) Dichloromethane, tetrahydrofuran and toluene: dried over molecular sieves 4A. 2) Methanol and acetonitrile: dried over molecular sieves 3A. All reactions sensitive to oxygen and/or moisture were conducted under an argon atmosphere.

1994

The dibutylstannylene acetals of carbohydrate-derived primary-secondary 1,2-diols 4, 104, 105 and 06 were found to be oxidized regiospecifically to corresponding $\alpha$-hydroxyketone derivatives in much better yields (81% to 95%) by N-bromosuccinimide in chloroform solution at room temperature than had previously been done with bromine. One of the products, 3-deoxy-1,2-O-isopropylidene-$\alpha$- scD-erythro-hexofuranos-5-ulose (10), exists to about 20% in solution as a mixture of dimers. One of the dimers can be obtained as a solid and its structure was determined tentatively by a combination of NMR experiments and MM3 molecular mechanics calculations.

European Journal of Inorganic Chemistry, 2007

The Journal of Organic Chemistry, 1991

The verbenone-derived cyclopentadienyl compound ( 1S,8S)-7,7,9,9-tetramethyltricyclo[6.1.1.02~6]deca-2,fi-dienyllithium (VCpLi) yielded a 3:2 mixture of exo and endo deuterio quench products upon reaction with DzO at -78 "C in THF. Stereochemical identification was achieved by NMR analysis of Diels-Alder addition products. Reaction of VCpLi with Me3SiC1 under the same Conditions gave rise to a 9:l exo:endo product mixture. Silatropic shifts were observed in these quench products. According to NMR analysis, VCpLi consists nearly exclusively of the exo-Li monomer in THF at +26 "C. However, at -80 "C a ternary equilibrium of an exo-Li monomer, an exo,exo-Li sandwich dimer, and an endo,endo-Li sandwich dimer in a 5.1:2.8:1.0 molar ratio has been detected. Thermodynamic parameters for the monomer-dimer equilibrium are AH" = -3.6 f 0.2 kcal/mol and ASo = -15.6 f 0.9 eu. Due to ring current effects, unusual upfield 6Li chemical shifta are observed: 6 (ppm) = -7.83 (exo monomer), -12.22 (exo,exo dimer), and -12.25

2016

Three novel compounds i.e. 1,3-dioxo-2,3-dihydro-1H-isoindol-2-yl)methyl]-1,10phenanthrolin-1-ium bromide (Phen-PHTH), {2-[2-methoxy-4-(3-methoxy-4-{2-[tris(propan-2-yl)silyl]ethynyl}phenyl)phenyl]ethynyl}tris(propan-2-yl)silane (4SGN-1) and 1-(3chloropropyl)-1,10-phenanthrolin-1-ium chloride (SND-Cl2B) were synthesized and characterized using NMR, MS, UV, FTIR and CNH analysis.