An improved synthesis of (4S,5S)-2,2-dimethyl-4-phenyl-1,3-dioxan-5-amine

The title compound is prepared in 78% yield using an improved one-pot procedure which does not require final purification.     

2,2-Dimethyl-5-(5-r-2-furfurylidene)-1,3-dioxan-4,6-diones. 1. Synthesis,properties, and structure

5-R-Furanaldehydes react with Meldrum's acid under Knoevenagel reaction conditions. The reaction products have s-cis conformation. The pK _a values of the electroneutral Lewis acids synthesized were determined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1325–1329, October, 1986.     

Synthesis, spectroscopic and DFT investigation of dimethyl-2-(5-acetyl-2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-yl)-3-(triphenylphosphinylidene)succinate

Dimethyl-2-(5-acetyl-2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-yl)-3-(triphenylphosphinylidene)succinate has been synthesized and characterized by elemental analysis, FT-IR and ¹H, ¹³C and ³¹P NMR. The vibrational wavenumbers, gauge including atomic orbital (GIAO) ¹H and ¹³C chemical shift values of title compound in the ground state have been computed with density functional theory method (DFT) and the B3LYP functional. The basis sets used are 6-311G(d,p) and 6-31G(d). The harmonic vibrational wavenumbers have been computed and the scaled values have been compared with the experimental FT-IR spectra. The complete assignments have been performed on basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. Most of the computed wavenumbers are found to be in good agreement with the observed spectrum.     

2,2-dimethyl-5-(5-r-furfurylidene)-1,3-dioxane4,6 diones 7. Synthesis,structure, and properties of 2,2dimethyl-5-(3-furfuryldiene and 3-thienylidene)-1,3dioxane-4,6-diones

The corresponding 3 furfurylidene(thienylidene)-dioxanediones were obtained by the reaction of 2,5-R,Rfuran(thiophen)-3-carbaldehydes with Meldrum's acid. It was shown by x-ray crystallographic analysis that they have the s-trans disposition at the C₍₂₎=C₍₃₎ bond of the five-membered heterocycle and an exocyclic multiple bond. The character of the conjunction in their molecules was considered in the light of data of x-ray crystallographic analysis, electronic spectra, and NMR. The corresponding 3-furfuryl(thienyl)]dioxanediones were obtained by the selective ionic hydrogenation of the exocyclic double bond.For part 6 see [1]Kuban State Technological University, Krasnodar 350072. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 899–905, July, 1995. Original article submitted October 25, 1994; revision submitted June 5, 1995.     

5-叔丁基-5-(1'-羟基-2'-甲基丙基)-2,2-二甲基-1,3-二氧六环的合成研究

为得到3,4-二取代双环硫化磷酸酯的中间体5-叔丁基-5-(1'-羟基-2'-甲基丙基)-2,2-二甲基-1,3-二氧六环, 通过5-叔丁基-5-甲酰基-2,2-二甲基-1,3-二氧六环与异丙基溴化镁反应没有得到目标化合物, 而得到了还原产物, 改用异丙基锂代替异丙基溴化镁反应后得到目标化合物, 通过超声波辅助反应, 大幅度提高了反应收率.     

外消旋6-（2-氨基-1-羟乙基）-2，2-二甲基-1，3-苯并二氧芑的拆分研究

以L-二对甲苯甲酰基酒石酸为拆分试剂,通过化学拆分法得到了旋光异构体(R)-6-(2-氨基-1-羟乙基)-2,2-二甲基-1,3-苯并二氧芑,产率高且光学纯度大于98%ee.     

5-[5-R-furfurylidene]-2,2-dimethyl-1,3-dioxane-4,6-diones 6. Synthesis,structure, and properties of substituted furylimino- and furfurylidenephosphoranes. Molecular and crystal structure of N-[5-(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidene)methyl-2-furylimino(triphenyl)phosphorane

Furylimino- and furfurylidenephosphoranes have been synthesized by sequential conversions of 5-unsubstituted and 5-methylfurfut),Iidetiedio.yanediones. The ylide fragment linked directly with the furfurylidenedioxanedione residue displays strong electron-donating properties, as a result of which resonance occurs in the system of conjugated bonds. The molecular and crystal structure of the iminophosphorane was studied by x-ray structural analysis and the resonance of the bonds in the molecule was confirmed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 335–344, March, 1994.     

Preparative synthesis of 2,2-dimethyl-5-(trifluoroacetyl)-1,3-dioxane-4,6-dione (2-trifluoroacetyl Meldrum's acid) and 2,2-dimethyl-6-(trifluoromethyl)-4H-1,3-dioxin-4-one and their synthetic usefulness as (trifluoroacetyl)ketene precursors

A simple and reliable method for the preparation of 2,2-dimethyl-5-(trifluoroacetyl)-1,3-dioxane-4,6-dione and 2,2-dimethyl-6-(trifluoromethyl)-4H-1,3-dioxin-4-one on a multigram scale was developed. These (trifluoroacetyl)ketene precursors were used in the hetero-Diels-Alder reaction with dialkylcyanamides and 1-ethoxyprop-1-yne, as well as in some reactions with nucleophiles.     

A practical synthesis of (+/-)-alpha-isosparteine from a tetraoxobispidine core

[reaction: see text] The title alkaloid was synthesized in racemic form from 3,7-diallyl-2,4,6,8-tetraoxo-3,7-diazabicyclo[3.3.1]nonane (7) by a regioselective diallylation reaction followed by double ring-closing olefin metathesis and exhaustive reduction. Tetraoxobispidine 7 was itself prepared in three simple operations from dimethyl malonate. The entire sequence to alpha-isosparteine was conducted on a multigram scale and proceeded without recourse to chromatography.     

Sterically strained conjugated systems containing a trisubstituted furan ring. Molecular structure of 5-dimethylamino-2,4-bis[2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidene)methyl]furan

We have synthesized sterically strained conjugated systems containing a trisubstituted furan ring. We have used X-ray diffraction to study the three-dimensional structure of 5-dimethylamino-2,4-bis[(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidene)methyl]furan. We have shown that such sterically strained systems undergo nonclassical deformations with distortion of mainly bond angles, but without loss of planarity.Kuban State Technological University, Krasnodar 350072, Russia; e-mail: organiscs@kubstu.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1476–1484, November, 1999.     

Synthesis of 5-[bromo(aryl)methyl]-2,2-dimethyl-1,3-oxazolidin-4-ones

A Darzens condensation of α-chloroacetamide with aromatic aldehydes furnished a series of 3-aryl-2,3-epoxypropionamides, which were further converted to 5-[bromo(aryl)methyl]-2,2-dimethyl-1,3-oxazolidin-2-ones.     

Reaction of 2-dimethylaminomethylene-1,3-diones with dinucleophiles. X. synthesis of 5-substituted ethyl or methyl 4-isoxazolecarboxylates and methyl 4-(2,2-dimethyl-1-oxopropyl)-5-isoxazolecarboxylate

Reaction of ethyl or methyl 2-dimethylaminomethylene-3-oxoalkanoates with hydroxylamine hydrochloride in methanol solution afforded in high yields the relative esters of 5-substituted 4-isoxazolecarboxylic acids II . These esters were hydrolyzed generally with concentrated hydrochloric acid-acetic acid mixtures to the corresponding carboxylic acids in satisfactory yields. Ethyl or methyl esters II isomerized with sodium ethoxide or methoxide, respectively, to the corresponding esters or hemiesters of 2-cyano-3-oxoalkanoic acids generally in excellent to satisfactory yields. Reaction of methyl 5,5-dimethyl-3-dimethylaminomethylene-2,4-dioxohexanoate with hydroxylamine hydrochloride afforded in moderate yield methyl 4-(2,2-dimethyl-1-oxopropyl)-5-isoxazolecarboxylate, which was converted by acid hydrolysis as above to 4-t-butyl-4-hydroxyfuro[3,4-d]isoxazol-6-(4H)-one.