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Thesis (Ph. D.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

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This thesis describes the synthesis and chemistry of alkyl 2,3-bis(trimethylstannyl)-2-alkenoates ((78) and (83)). It was shown that these compounds could be readily transformed into useful intermediates for the synthesis of functionalized, stereochemically defined tetrasub-stituted alkenes (87) and tricyclic dienes of general structure (322A). The synthesis and chemistry of compounds (277) and (278) is also described. The palladium(O)-catalyzed addition of hexamethylditin to a variety of α,β-acetylenic esters (90), afforded in a stereoselective manner, the corresponding alkyl (Z)-2,3-bis(trimethylstannyl)-2-alkenoates (83). Subsequent thermolysis of these compounds afforded the corresponding alkyl (E)-2 , 3-bis(trimethylstannyl)-2-alkenoates (78). It was found that treatment of alkyl (E)- and (Z)-2,3-bis(tri-methylstannyl)-2-alkenoates with methyllithium at low temperature, followed by reaction of the resultant nucleophilic intermediate with a variety of alkylating agents, afforded the trisubstituted vinylstannanes (80). On the other hand, successive treatment of methyl w-halo-2,3-bis-(trimethylstannyl)-2-alkenoates (202) with methyllithium and HMPA provided a facile route to cyclic β-trimethylstannyl α,β-unsaturated esters (203). Compounds (80) were readily converted into vinyl iodides of general structure (219) in which W is a functionalized group derived from the CO₂R moiety. These latter compounds served as useful intermediates for the synthesis of functionalized, stereochemically defined tetrasubstituted alkenes (87). For example, treatment of compounds (219) with 1.1 or 2.2 equiv of n-butyllithium at -78°C afforded the corresponding vinyllithium species (86) , which could either be alkylated directly or further transposed into the organocopper(I) reagent (263A) and then alkylated, to afford in each case, the tetrasubstituted alkenes (87). The Pd(0)-catalyzed addition of tri-n-butylstannyltrimethylgermane (276) to a variety of α,β-acetylenic esters (90) afforded the corresponding compounds (277) and (278) in a ratio of approximately 3:1, respectively. Treatment of the (E) isomers (277) with n-butyllithium at -98°C, followed by alkylation of the resultant nucleophilic intermediate afforded the corresponding trisubstituted vinylgermanes (293). One of these latter compounds was readily converted into the iodo bromide (308), which is potentially synthetically equivalent to the d,a synthon (310). When the enolate anion of compounds (203) was successively treated with HMPA and compound (308) the esters (311) were obtained. The Pd(0) catalyzed intramolecular coupling of the vinylstannane-vinyl iodide moieties of (311) provided a facile route to the bicyclic triene esters (312). Similarly, alkylation of the enolate anion of compounds (203) with (325) (which was readily obtained from (203), in which n - 1), followed by the Pd(0)-catalyzed coupling of the resulting alkylated material afforded the tricyclic diene esters (322A). [Formula Omitted] / Science, Faculty of / Chemistry, Department of / Graduate

No description available.

Organotin compounds (OTs), in particular tributyltin (TBT) and triphenyltin (TPT), have caused widespread adverse effects on marine organisms ever since their wide application as biocides in 1960s. For instance, TBT can induce the abnormal development of imposex in marine gastropods, and inhibit development and growth in oysters. A mandatory global ban on the use of OT-based antifouling systems, therefore, has been enacted by the International Maritime Organization to minimize their environmental impacts since September 2008. As a result, it is anticipated to see a reduction of OT contamination in the marine environment around the world. This study, therefore, primarily aims to test the hypothesis that there is a reduction of both OT contamination and its associated adverse impact to a common biomonitor, the rock shell Reishia clavigera along the coast in Hong Kong and Shenzhen, China through a series of field-based investigations. Before the field study, a method was successfully developed to simultaneously quantify the concentrations of six common OTs (i.e., mono-BT, di-BT and TBT; mono-PT, di-PT and TPT) in molluscan tissues using gas chromatography-mass spectrometry. These six compounds coexist in marine environments. They are highly toxic to marine organisms and are able to induce imposex in gastropods like R. clavigera. First, a territory-wide survey on tissue concentrations of the OTs and imposex status in R. clavigera collected from 28 coastal sites of Hong Kong was conducted in 2010. The results indicated that all female R. clavigera suffered from imposex, and all rock shells contained high TPT concentrations. A probabilistic ecological risk assessment revealed that 17.6% of R. clavigera across all sites were at risk due to exposure to TPT, whereas the risk associated with TBT was relatively low. The same species collected from Dapeng Bay and Daya Bay, Shenzhen also exhibited high tissue concentrations of TPT. Second, R. clavigera transplanted from relatively clean sites to polluted sites for six months showed increases in both imposex status and tissue concentration of OTs, confirming the association between OT contamination and imposex development. Third, a 25-month population dynamics study of R. clavigera showed a limited recruitment of the species in the polluted sites. To verify if the observed OT contamination was widespread to other marine species in Hong Kong waters, a survey on the tissue concentrations of OTs in 11 local seafood species was conducted. Among them, the tongue sole Paraplagusia blochii had the highest tissue concentration of total OTs, with TPT as the most abundant residue. Potential health risk for consuming this benthic fish species was identified as both hazard quotient of TPT and hazard index exceeded unity. The overall results demonstrate that the coastal marine environments in this region are still heavily contaminated with OTs especially TPT, and there is no obvious sign of recovery of R. clavigera populations. Hopefully, with further scientific investigations, both Hong Kong and China governments will take appropriate management actions to control the use and release of these priority pollutants with a view to safeguarding the marine ecosystem and human health in this region. / HKU 3 Minute Thesis Award, 2nd Runner-up (2013) / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

In Part 1, the Diels-Alder adducts of trimethyl cyclopentadienylstannane (I.3) with maleic anhydride and fumaronitrile are prepared in 61% yield. The molecular structure of the adduct with maleic anhydride (1.6) is unequivocally established as 7-syn-trimethy1stannyl-endo- bicyclo[2.2.1]hept-5-enyl-2,3-dicarboxy1ic anhydride by single crystal X-ray structure analysis. In Part II, the high yield preparation of some new S-a1ky1-Saryl- N-p-toluenesu1fonylsu1foximines, by ruthenium tetroxide oxidation of the corresponding su1filimine, is described. Dehydrochlorination of S-chloroethy1-N-p-toluenesu1fonyl-S-p-toly1su1foximine and its S-phenyl analog with triethylamine gives the previously unknown N-p-to1uenesu1fony1- S-p-to1y1-S-viny1sulfoximine (II.17) and its S-phenyl analog. The Diels-Alder reaction of II.17 with a variety of 1,3-dienes and the known N-phtha1imido-S-p-tolyl-vinylsu1foximine (11.14) and the previously unreported S-p-nitropheny1-N-phtha1imido-viny1su1foximine (11.39) with cyclopentadiene are described. All of the reactions give mixtures of the possible adducts. The configuration of the major diastereomer (II.19d) of the adducts of II.14 with cyclopentadiene is known from a single crystal X-ray structure analysis. The structures of the other adducts are determined by ¹H NMR spectroscopic analysis. Chemical correlation of II.19d with the adducts of II.17 with cyclopentadiene confirm the assignment made by ¹H NMR. A competition Die1s-Alder reaction between II.17 and p-toly1-viny1sulfone shows that the vinylsulfoximine is more reactive. Sodium amalgam reduction of the cyclohexadienyl adducts of II.17 gives bicyclo[2.2.2Joctene and hydrazine in allyl alcohol reduction of adduct II.19d gives the corresponding sulfoxide II.20d.

Chapter 1 describes the reactivities of bisgermavinylidene [(Me 3SiN=RPh2)2C=Ge→Ge=C(PPh2=NSiMe 3)2] (25). With the use of CpMnCO2(THF), Mn2(CO)10 and group 11 metal halides, manganese-germavinylidene complexes and germavinylidyl group 11 metal complexes were prepared respectively. Radical reaction of 25 with 2,2,6,6-tetramethylpiperidine N-oxide affords [(Me3SiN=RPh2)2C=Ge(ONCMe2C 3H6CMe2)2] (40). Cycloadditon reactions of 25 were studied. The reaction of 25 with benzil, azobenzene or 3,5-di-tert-butyl-o-benzoquinone affords [(Me3SiN=PPh2)2C=Ge{O(Ph)C=C(Ph)O}] (41), [(Me3SiN=PPh2)2C=Ge( o-C6H4NHNPh)](42) and [(Me 3SiN=PPh2)2C=Ge=C-(PPh2=NSiMe 3)2] (44), respectively. The C=Ge bond of 25 can undergo cycloaddition reactions with Me3SiN 3, Me3SiCHN2 or AdNCO (Ad = adamantly) to give [(Me3SiN=PPh2)2CGeN(SiMe3)N=N] (46), [(Me3SiN=PPh2)2C-GeN=NCH-SiMe 3] (48) and [(Me3SiN=PPh2)2 CGeN(Ad)C-O] (47), respectively. Furthermore, 1,2-addition products of rhodium(I) and tin(IV) complexes were prepared from the reaction of 25 with (cod)RhCl and (nBu) 3SnN3, respectively. The syntheses of bimetallic chlorides [(Me3SiN=PPh2)2(GcCl)CMn(mu-Cl)]2 (51) and [(Me3SiN=PPh2)2(GeCl)CFeCl] (52) are also reported. / Chapter 2 concerns the reactivities of bis(iminophosphorano)methanide tin(II) chloride [HC(PPh2=NSiMe3)2SnCl] ( 79). The reactivity of the lone pair in 79 was studied. The reaction of 79 with benzil or 3,5-di-tert-butyl- o-benzoquinone gives the corresponding cycloaddition products. Treatment of 79 with NaN3 or AgOSO2CF3 affords the corresponding substituted heteroleptic stannylenes. The reaction of 79 with W(CO)5THF gives an adduct [HC(PPh 2=NSiMe3)2(Cl)Sn→W(CO)5] ( 81). Compound 79 reacts with Fe{N(SiMe3) 2}2 to afford [HC(PPh2=NSiMe3) 2Fe(mu-Cl)]2 (86). Moreover, treatment of 79 with LiC≡CPh gives [HC(PPh2=NSiMe3) 2C(Sn)=C(Ph)Sn(C≡CPh)2]2 (87). / Chapter 3 deals with the preparation and characterization of group 14 bis(thiophosphinoyl) metal complexes. The newly developed ligand [(S=PPr i2CH2)2-C5H 3N-2,6] (126) undergoes metalation with nBuLi or (nBu)2Mg to afford the lithium complex [Li{(S=PPri 2CH)(S=PPi2CH2)C 5H3N-2,6}(Et2O)] (127) and magnesium complex [Mg(S=PPri2CH)2C 5H3N-2,6] (128), respectively. 1,3-Distannylcyclobutane and 1,3-diplumbacyclobutane were prepared from treatment of 126 with M{N(SiMe3)2}2 (M Sn, Pb) by the amine-elimination reaction. Furthermore, compound 127 reacts with GeCl2.dioxane or SnCl2 to afford digermylgermylene Ge[GeCl2{(S=PPr i2CH)(S=PPri 2CH2)C5H3N-2,6}]2 ( 131) and ionic tin(II) complex [{C5H3N-2,6-(CH 2PPri2=S)(CHPPr i2=S)}SN+][SnCl3 -] (134), respectively. / Chapter 4 describes the conclusion of the first three chapters. The future works of the first three chapters were also reported. / This thesis is focused on four areas: (i) the reactivities of bisgermavinylidene; (ii) the reactivities of bis(iminophosphorano)methanide tin(II) chloride; (iii) the synthesis of group 14 bis(thiophosphinoyl) metal complexes and (iv) conclusions and future works. / Kan, Kwok Wai. / "Aug 2007." / Adviser: Kevin W. P. Leung. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1007. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

Kaohsiung Harbor is the largest international sea port in Taiwan, a lot of ships around the world pass in and out frequently, the pollution of organotin is very serious in the harbor area. Love River and Chien-Chen River may be polluted by the seawater tidal action from the Kaohsiung harbor. Domestic, industrial and agricultural wastewaters discharged into the upstream sections may also cause the pollution of organotin. The purposes of this study were to understand sources of organotin pollution by analying the content of organotin compounds and to monitor the organotin pollution of the rivers in Kaohsiung. Samples including surface sediments and riverwaters were collected from nineteen stations of Love River and Chien-Chen River. The results revealed that concentrations of MBT, DBT and TBT in the riverwaters of Love River varied between 13.4-43.6, 2.6-9.9 and ND-13.5 ng/L as tin. The concentrations of MBT, DBT and TBT in the riverwaters of Chien-Chen River were 3.1-28.1, 2.1-10.9 and ND-9.1 ng/L as tin, respectively. The concentrations of MBT, DBT and TBT in the surface sediments of Love River varied between 20.6-92.3, 7.6-26.2 and ND-15.4 ng/g as tin. The concentrations of MBT, DBT and TBT in the surface sediments of Chien-Chen River were in the range of 22.4-70.0, 6.4-14.1, ND-31.9 ng/g as tin, respectively. MBT and DBT were detected in all the samples of all the sampling stations of Love River and Chien-Chen River. Distribution of organotin compounds in riverwaters and surface sediments showed a consistency between these two rivers. No phenyltin pollution was detected at all stations, probably due to the decline in agricultural activities and the ban on utilizing triphenyltin acetate as pesticide. Except the highest organotin pollution appeared in the outfall of Love River and Chien-Chen River, other high values of pollution were found near the upper reaches of both rivers.