Synthesis of 1,7-dioxaspiro[5.5]undecanes and 1-oxa-7-thiaspiro[5.5]undecanes from exo-glycal

A new spirocyclization was developed for the synthesis of 1,7-dioxaspiro[5.5]undecanes and 1-oxa-7-thiaspiro[5.5]undecanes by reaction of exo-glycal with aryl alcohols or thiophenols in the presence of Lewis acid BF₃·OEt₂. The reaction proceeded through tandem Ferrier rearrangement, glycosylation, and Friedel–Crafts alkylation to provide the corresponding products in good to excellent yields.     

Flexible synthesis of enantiomerically pure 2,8-dialkyl-1,7-dioxaspiro[5.5]undecanes and 2,7-dialkyl-1,6-dioxaspiro[4.5]decanes from propargylic and homopropargylic alcohols

A new approach to enantiomerically pure 2,8-dialkyl-1,7-dioxaspiro[5.5]undecanes and 2,7-dialkyl-1,6-dioxaspiro[4.5]decanes is described and utilizes enantiomerically pure homopropargylic alcohols obtained from lithium acetylide opening of enantiomerically pure epoxides, which are, in turn, acquired by hydrolytic kinetic resolution of the corresponding racemic epoxides. Alkyne carboxylation and conversion to the Weinreb amide may be followed by triple-bond manipulation prior to reaction with a second alkynyllithium derived from a homo- or propargylic alcohol. In this way, the two ring components of the spiroacetal are individually constructed, with deprotection and cyclization affording the spiroacetal. The procedure is illustrated by acquisition of (2S,5R,7S) and (2R,5R,7S)-2-n-butyl-7-methyl-1,6-dioxaspiro[4.5]-decanes (1), (2S,6R,8S)-2-methyl-8-n-pentyl-1,7-dioxaspiro[5.5]undecane (2), and (2S,6R,8S)-2-methyl-8-n-propyl-1,7-dioxaspiro[5.5]undecane (3). The widely distributed insect component, (2S,6R,8S)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane (4), was acquired by linking two identical alkyne precursors via ethyl formate. In addition, [(2)H(4)]-regioisomers, 10,10,11,11-[(2)H(4)] and 4,4,5,5-[(2)H(4)] of 3 and 4,4,5,5-[(2)H(4)]-4, were acquired by triple-bond deuteration, using deuterium gas and Wilkinson's catalyst. This alkyne-based approach is, in principle, applicable to more complex spiroacetal systems not only by use of more elaborate alkynes but also by triple-bond functionalization during the general sequence.     

Straightforward synthesis of 1,6-dioxaspiro[4.4]nonanes

Diols 2, easily prepared by a DTBB-catalysed lithiation of the dithioether 1 in the presence of different carbonyl compounds, react with ozone in dichloromethane at −78 °C leading, after treatment with thiourea at 20 °C, to the corresponding substituted 1,6-dioxaspiro[4.4]nonanes 3.     

Syntheses of Racemic and Optically Active 4-Hydroxy-2-hydroxymethyl-1,7-dioxaspiro[5.5]undecanes

Racemic and optically active 4-hydroxy-2-hydroxymethyl-1,7-dioxaspiro[5.5]undecanes were prepared in six steps from butane-1,2,4-triol and valerolactone with the longest linear sequence being four steps.     

Dioxolane-to-bridged acetal-to-spiroketal via ring-closing metathesis and rearrangement: a novel route to 1,7-dioxaspiro[5.5]undecanes

Several examples of 1,7-dioxaspiro[5.5]undecane spiroketal systems have been synthesized from the common bicyclic intermediate 1 via acid-catalyzed rearrangement. Intermolecular ketalization of C(2) symmetric diene diol 3 with ketone 9 and then desymmetrization by ring-closing metathesis rapidly constructs bicyclic acetal 1. The locked conformation and steric bias of 1 allow stereoselective functionalization of one or both double bonds before spiroketalization.     

Synthesis of benzene-fused 1,7,8-trioxa-spiro[5.6]dodecanes

Two novel organic peroxides with one or two benzene rings fused to a 1,7,8-trioxaspiro[5.6]dodecan framework were synthesized, which provided the first examples of employing Kobayashi’s methodology in the synthesis of seven-membered peroxy rings. CSA was found to be a potent catalyst for introduction of the hydroperoxyl group, making a useful complement to Kobayashi’s methodology in constructing spiroperoxides.     

Straightforward synthesis of 1,7-dioxaspiro[4.4]nonanes

The reaction of 2-chloromethyl-3-(2-methoxyethoxy)prop-1-ene with an excess of lithium powder and a catalytic amount of naphthalene (2.5%) in the presence of a carbonyl compound (E¹=R¹R²CO) in THF at −78 to 0 °C, followed by the addition of an epoxide [E²=R³R⁴C(O)CHR⁵] at 0 to 20 °C leads, after hydrolysis, to the expected methylidenic diols. These diols, in the presence of iodine and silver(I) oxide in dioxane-water, undergo double intramolecular iodoetherification to give the corresponding 1,7-dioxaspiro[4.4]nonanes, which in addition can be easily oxidised to a variety of 1,7-dioxaspiro[4.4]nonan-6-ones.     

2,8-二甲基-1,7-二氧杂螺[5,5]十一烷的合成

果蝇 ( Tephritidae)对水果生产有严重的危害 .热带果蝇寿命较长 ,具有很强的迁徙能力和繁殖能力 .因此开展果蝇生物防治和控制措施的相关研究具有重要的意义 [1,2 ] .Baker等 [3]发现性成熟的雌B.dorsalis果蝇 ,性腺分泌物中包含有螺环缩酮化合物 2 ,8-二甲基 - 1 ,7-二氧杂螺 [5 ,5 ]十一烷 ( 1 ) .Bactrocera Latifrons( Hendel)果蝇的雄性腺体分泌物中也存在螺环缩酮 1 [4 ] ,另外在 rove甲虫腹梢分泌物中也分离出 1 [5] ,螺环缩酮不仅作为性信息素组分存在于许多果蝇腺体中 ,而且作为结构单元存在于许多复杂的有强烈生理活性的天然…     

Synthesis of the enantiomers of 1,7-dioxaspiro[5.5]undecane and 4-hydroxy 1,7-dioxaspiro[5.5]undecane,the components of the olive fly pheromone

The enantiomers of the olive fly pheromone (1 and 4) were synthesized from ($\text{S}$)-malic acid in amounts sufficient for the biological test.     

Synthesis of the optically active forms of 4,10-dihydroxy-1,7-dioxaspiro[5.5]undecane and their conversion to the enantiomers of 1,7-dioxaspiro[5.5]undecane,the olive fly pheromone

Both the enantiomers of l,7-dioxaspiro[5.5]undecane, the major component of the pheromone of the olive fly (Dacus oleae), were synthesized from (S)-malic acid.     

Energetics of oxaspirocycle prototypes: 1,7-dioxaspiro[5.5]undecane and 1,7,9-trioxadispiro[5.1.5.3]hexadecane

The relative gas-phase energetics of several low-lying isomers of 1,7-dioxaspiro[5.5]undecane and 1,7,9-trioxadispiro[5.1.5.3]hexadecane have been calculated with second-order Mller-Plesset perturbation theory and basis sets as large as aug-cc-pVQZ. Relative energies in THF, dichloromethane, acetone, and DMSO have been estimated with corrections from polarized continuum model calculations at the B3LYP/6-311+G(d) level. In the most stable conformation of 1,7-dioxaspiro[5.5]undecane, both rings adopt chair conformations, and both oxygens are axially disposed (2A). It is more than 2 kcal mol(-1) more stable than all the other conformers. In agreement with previous work, the "twist-boat" trans isomer (3A) is the most stable isomer of 1,7,9-trioxadispiro[5.1.5.3]hexadecane. However, in contrast to this earlier study, an "all-chair" conformation (3B) is found to be the most stable cis isomer of 1,7,9-trioxadispiro[5.1.5.3]hexadecane (E approximately 0.5 kcal mol(-1) in acetone and DMSO). Gauge-independent atomic orbital computations at the B3LYP/6-311+G(d) level indicate that this is the only cis isomer with (13)C NMR chemical shifts that are qualitatively consistent with the experimental spectra.     

Claisen self-condensation/decarboxylation as the key steps in the synthesis of C2-symmetrical 1,7-dioxaspiro[5.5]undecanes

A convenient method for the synthesis of functionalised 1,7-dioxaspiro[5.5]undecanes using acid-catalysed spiroketalisations of substituted dihydroxyketones is described. The dihydroxyketones were readily prepared from appropriately substituted hydroxy esters via Claisen self-condensation followed by decarboxylation.     

Regioselective synthesis of 1,7-dioxaspiro[4.4]nonanes from a trimethylenemethane dianion synthon

2-Chloromethyl-3-(2-methoxyethoxy)prop-1-ene behaves as a versatile trimethylenemethane dianion synthon, precursor of a variety of methylidenic diols obtained by DTBB-catalysed lithiation in the presence of a carbonyl compound (E¹=R¹R²CO) in THF at −78 to 0 °C, followed by the addition of an epoxide [E²=R³R⁴C(O)CHR⁵] at 0 to 20 °C and final hydrolysis. These diols undergo double intramolecular iodoetherification in the presence of iodine and silver(I) oxide in THF or dioxane-water, to give the corresponding 1,7-dioxaspiro[4.4]nonanes, which can be easily oxidised to a variety of 1,7-dioxaspiro[4.4]nonan-6-ones. These skeletons are present in a wide series of natural products.     

The First Synthesis of Functionalized Oxacalix[4]crown Ethers

O-alkylation and cyclization of 25,27-dihydroxy-4,6,16,18-tetranitro-oxacalix[4]arene were performed with mono- and bifunctional alkylating agents under basic conditions. In this way several 1,3-alt oxacalix[4]crown-4, 5 and 6 ethers were synthesized and characterized     

2—取代—1,7—二氧螺（4.4）壬—8—酮的合成研究

分别用Ｋ２ＣＯ３，１，５－二氮双环（４．３．０）壬－５－烯（ＤＢＮ）和四丁基氟化铵（ＴＢＡＦ）等碱催化３－（３－羟基丙基）－γ－丁烯酸内酯的分子内Ｍｉｃｈｅａｌ加成反应合成了２－取代－１，７－二氧螺（４．４）壬－８－酮     

Synthesis of the enantiomers of 1,7-dioxaspiro[5.5]undecane, 4-hydroxy-1,7-dioxaspirol[5.5]undecane and 3-hydroxy-1,7-dioxaspiroi[5.5]undecane : The components of the olive fruit fly pheromone

All of the enantiomers of the title compounds, the components of the pheromone of the olive fruit fly ($\text{Dacus}$$\text{oleae}$ Gmelin), were synthesized from ($\text{S}$)-malic acid.     

Synthetic studies towards 4,10-diaza-1,7-dioxaspiro[5.5]undecanes: access to 3-aza-6,8-dioxabicyclo[3.2.1]octan-2-one and 2H-1,4-oxazin-3(4H)-one frameworks

Synthetic approaches towards 4,10-diaza-1,7-dioxaspiro[5.5]undecanes starting from 1,3-dichloroacetone and solketal derivatives are explored. The method relies on the preparation of a key bis-substituted dihydroxy-protected oxime, which would undergo a final acidic deprotection-spiroacetalization process. Although the desired diazaspiroketal framework could not be obtained, our conditions led to the unexpected 3-aza-6,8-dioxabicyclo[3.2.1]octan-2-one 18 or to the oxazinone 32 in good yields.     

Synthesis and properties of 1,6-dioxaspiro[4.4]nonane and its derivatives (review)

Data on methods of synthesis and the chemical properties of 1,6-dioxaspiro-[4.4]nonane and its derivatives are correlated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1155–1168, September, 1986.     

Synthesis of 6-(Bromomethyl)-4-methoxy-5,6,7,8-tetrahydropyrido- [3,2-d]pyrimidin-2-ol from 6-Methylpyrimidine-2,4-diol

6-(Bromomethyl)-4-methoxy-5,6,7,8-tetrahydropyrido[3,2-d]pyrimidin-2-ol(compound 9) was synthesized from 6-methylpyrimidine-2,4-diol(compound 1) through the crucial steps of 6-methyl alkylating and intramolecular cyclization. The assignment of the structure of compound 9 was performed by its spectral data, ¹H NMR, ¹³C NMR, HMBC, and HRMS spectra.     

Synthesis and transformation of 2-methyl-3-acetyl-1,6-dioxaspiro[4,4]-2-nonene

Conclusions 2-Methyl-3-acetyl-1,6-dioxaspiro[4,4]-2-nonene is formed when tetrahydrofurfurole is reacted with acetylactone, from which some new furan, cyclopentenone, pyrrole and pyrazole derivatives were obtained.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 908–910, April, 1984.