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.     

An entry to 1,6-dioxaspiro[4.6]undecanes and 1,7-dioxaspiro[5.6]dodecanes

Ketones 11a-c obtained by iterative alkylation of acetone N,N-dimethylhydrazone with iodides 6 and 8a,b or epoxide 9 followed by SiO₂/H₂O-induced cleavage of the hydrazone were quantitatively transformed into 1,6-dioxaspiro[4.6]undecanes 12a,c and 1,7-dioxaspiro[5.6]dodecanes 12b using Yb(OTf)₃ in CH₃CN.     

Spirans XXI. Synthesis of silaazaspiro[4.5]decanes and silaazaspiro[5.5]undecanes

N-(2-Dimethylaminopropyl)-8,8-dimethyl-8-sila-2-azaspiro[4.5]decane ( 1 ) and N-(3-dimethyl-aminopropyl)-9,9-dimethyl-9-sila-3-azaspiro[5.5]undecane ( 2 ) have been synthesized from 4,4-dimethyl-4-silacyclohexanone ( 5 ). Biological evaluation of 1 and 2 indicated cytotoxic action against human cancer cells grown in tissue culture.     

A direct synthesis of 1,7-dioxaspiro[4.5]decanes from the new 3-methylidenepentane-1,5-dianion synthon

4-Phenylsulfanyl-2-(2-phenylsulfanylethyl)but-1-ene (2) has proved to be an appropriate and new 3-methylidenepentane-1,5-dianion synthon. The reaction of 2 with an excess of lithium powder and a catalytic amount of DTBB (2.5%) in the presence of a carbonyl compound in THF at 0 °C, leads, after hydrolysis, to the expected methylidenic diols 3. These diols undergo double intramolecular iodoetherification promoted by a silver salt, to furnish the corresponding 1,7-dioxaspiro[4.5]decanes (4) in very high yields. The oxidation of compounds 4 to the corresponding lactones is also studied.     

Spirans XX. Synthesis of 8,8-dialkylazaspiro[4.5] decanes and 9,9-dialkylazaspiro[5.5]undecanes

N-(2-Dimethylaminopropyl)-8,8-dimethyl-2-azaspiro[4.5]decane ( 1 ), N-(2-dimethylaminopropyl)-8,8-diethyl-2-azaspiro[4.5]decane ( 2 ), N-(3-dimethylaminopropyl)-9,9-dimethyl-3-azaspiro[5.5]undecane ( 3 ), and N-(3-dimethylaminopropyl)-9,9-diethyl-3-azaspiro[5.5]undecane ( 4 ) have been synthesized from 4,4-dimethylcyclohexanone ( 5 ) and 4,4-diethylcyclohexanone ( 6 ). Biological evaluation of these amines showed significant inhibition of cancer cell growth in human cancer cells grown in tissue culture.     

A simple,efficient, two-step synthesis of symmetric 2,7-dialkyl-1,6-dioxaspiro[4.4]nonanes

A two-step synthesis of symmetric 2,7-dialkyl-1,6-dioxaspiro[4.4]nonanes has been achieved by double Michael addition of nitromethane with two moles of enones on Amberlyst A21, followed by in situ reduction with sodium borohydride, then spontaneous spiroketalization of the obtained nitrodiol, by the Nef reaction under acidic conditions, affords the title compounds in good yields.     

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.     

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…     

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.     

A new 3-methylidenepentane-1,5-dianion synthon: synthesis of perhydropyrano[2,3-b]pyrans and 1,7-dioxaspiro[4.5]decanes

4-Phenylsulfanyl-2-(2-phenylsulfanylethyl)but-1-ene (2) has proved to be an appropriate and new 3-methylidenepentane-1,5-dianion synthon. The reaction of 2 with an excess of lithium powder and a catalytic amount of DTBB (2.5%) in the presence of a carbonyl compound in THF at 0 °C, leads, after hydrolysis, to the expected methylidenic diols 3. These diols when subjected to successive hydroboration-oxidation and final oxidation, undergo spontaneous cyclisation to furnish a series of cis-perhydropyrano[2,3-b]pyrans (4) in a highly diastereoselective manner (>99% de). Additionally, diols 3 also undergo double intramolecular iodoetherification promoted by a silver salt, to furnish the corresponding 1,7-dioxaspiro[4.5]decanes (6) in very high yields.     

A synthesis of 1,6-dioxaspiro[4.5]dec-3-enes.

Base-catalysed rearrangement of a 2-alkynyl-tetrahydropyran generates an allenol ether intermediate which undergoes acid-catalysed cyclisation to the 1,6-dioxaspiro[4.5]dec-3-ene system.     

Organoselenium mediated asymmetric cyclizations. Synthesis of enantiomerically pure 1,6-dioxaspiro[4.4]nonanes

The asymmetric cyclization of 1-hydroxyoct-7-en-4-one, promoted by camphorselenenyl tetrafluoroborate, generated from camphor diselenide and silver tetrafluoroborate in dichloromethane at room temperature, afforded a mixture of two diastereoisomeric E- and two diastereoisomeric Z-2-[(camphorseleno)methyl]-1,6-dioxaspiro[4.4]nonanes. These were separated by medium pressure liquid chromatography and then deselenenylated with triphenyltin hydride and AIBN to give enantiomerically pure 2-methyl-1,6-dioxaspiro[4.4]nonanes. The camphorseleno group was also substituted by an allyl function using allyltributyltin in the presence of AIBN.     

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.     

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.     

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.     

Spirans XXII. Synthesis of 4,4-dialkyl-4-germacyclohexanone and 8,8-dialkyl-8-germaazaspiro [4.5] decanes

4,4-Dialkyl-4-germacyclohexanones have been synthesized and their reactions studied. The diethyl ketone has been converted into N-(-dimethylaminopropyl)-2 aza-8,8-diethyl-8-germaspiro[4.5]decane ( 16 ). The biological properties of 16 have been examined in some detail. The reactions of this new ketone with some other reagents are reported.