Search

Alkylation of the hippurate esters of trans 2-(p-substituted phenyl)cyclohexanol with benzyl bromide affords phenylalanine derivatives in high chemical yield. The reaction stereoselectivity varies from 20 to >98% depending on the aromatic group in the cyclohexyl auxiliary. A model that correctly predicts the sense of the induction is proposed.Key words: enolate conformation, pi-stacking, 2-phenylcyclohexanol, chiral auxiliary.

Alkylation of the hippurate esters of trans 2-(p-substituted phenyl)cyclohexanol with benzyl bromide affords phenylalanine derivatives in high chemical yield. The reaction stereoselectivity varies from 20 to >98% depending on the aromatic group in the cyclohexyl auxiliary. A model that correctly predicts the sense of the induction is proposed.

Nimesulide is a nonsteroidal anti-inflammatory drug recently detected in equine blood and urine samples taken at the race track. The detection of the drug in a blood sample led to the identification of an unknown thin-layer chromatographic (TLC) spot in track urine samples as a metabolite of nimesulide. Characterization of the unknown TLC spot and comparison with the synthesized compound shows that the unknown TLC spot is a previously unreported equine metabolite of nimesulide. The metabolite was identified as resulting from the reduction of the nitro group on nimesulide to an amino group. This reduced nitro metabolite (4-amino-2-phenoxy-methanesulfonanilide) is a major metabolite of nimesulide in the equine.

Benzylation of chiral esters of N-acylglycines using various bases and additives was examined. No C-alkylation was observed with one equivalent of base. Diastereoselectivities were dependent on the amount of additive, the nature of the N-acyl group, and the chiral ester. A model to account for the degree and sense of the stereoselectivity is proposed.

Alkylations of anions derived from dipeptides with a glycine at the C-terminus have been investigated. A hydrocarbon sedition in the N-terminal residue does impart some asymmetric induction. The use of a chiral ester derivative provides the potential for double asymmetric induction and good selectivity. With an aspartyl residue at the N-terminus, problems were encountered due to competing side reactions. The use of an azetidinone could circumvent some of these, but the observed induction was not high.

The trimethylsiyl ether 7 derived in two steps from camphor underwent ring expansion via an acylion rearrangement to afford two products (8 and 9) when desilylation was attempted. Compound 9 was stable but 8 was oxidized in air to homocamphoric acid anhydride 11. Key words: camphor, acyloin rearrangement.

Alkylations of anions derived from dipeptides with a glycine at the C-terminus have been investigated. A hydrocarbon sedition in the N-terminal residue does impart some asymmetric induction. The use of a chiral ester derivative provides the potential for double asymmetric induction and good selectivity. With an aspartyl residue at the N-terminus, problems were encountered due to competing side reactions. The use of an azetidinone could circumvent some of these, but the observed induction was not high.

Contrary to a published report, C-alkylation of methyl hippurate requires two equivalents of base. The choice of additive (TMEDA or HMPA) influences the result. Deuteration of the enolate gives results which depend on both the deuterium source and the nature of the additive.

The trimethylsiyl ether 7 derived in two steps from camphor underwent ring expansion via an acylion rearrangement to afford two products (8 and 9) when desilylation was attempted. Compound 9 was stable but 8 was oxidized in air to homocamphoric acid anhydride 11. Key words: camphor, acyloin rearrangement.

Dissolving metal reduction of known enone S affords predominantly the racemic form of title ketone ( 3 ) whereas catalytic reduction gives the meso isomer 6 . Neither ketone 3 nor alcohol 4 could be satisfactorily resolved. Asymmetric synthesis of (−)− 3 and (+)− 4 (ee=91 %) was effected from ketone (+)- 13 .

The purpose of this paper is to define standard methods for effective and efficient image-based dimensional metrology for microlithography applications in the manufacture of integrated circuits. This paper represents a consensual view of the co-authors, not necessarily in total agreement across all subjects, but in complete agreement on the fundamentals of dimensional metrology in this application. Fundamental expectations in the conventional comparison-based metrology of width are reviewed, with its reliance on calibration and standards, and how it is different from metrology of pitch and image placement. We discuss the wealth of a priori information in an image of a feature on a mask or a wafer. We define the estimates of deviations from these expectations and their applications to effective detection and identification of the measurement errors attributable to the measurement procedure or the metrology tool, as well as to the sample and the process o fits manufacture. Although many individuals and organizations already use such efficient methods, industry-wide standard methods do not exist today. This group of professionals expects that, by placing de facto standard meth-odologies into public domain, we can help reduce waste and risks inherent in a "spontaneous" technology build-out, thereby enabling a seamless proliferation of these methods by equipment vendors and users of dimensional metrology. Progress in this key technology, with the new dimensional metrology capabilities enabled, leads to improved perform-ance and yield of IC products, as well as increased automation and manufacturing efficiency, ensuring the long-term health of our industry.

(x unspecified) [54287-50-2] C4H8O5S (MW 168.19) (x = 1) [20769-58-8; 35346-47-5] C4H8O8S2 (MW 248.26) InChI = 1S/C4H8O2.O3S/c1-2-6-4-3-5-1;1-4(2)3/h1-4H2; InChIKey = HGBGABMSTHQFNJ-UHFFFAOYSA-N (x = 2) [52922-31-3] C4H8O11S3 (MW 328.33) InChI = 1S/C4H8O2.2O3S/c1-2-6-4-3-5-1;2*1-4(2)3/h1-4H2;; InChIKey = NTHGLQVCZIRQNS-UHFFFAOYSA-N (x = 3) [52922-32-4] InChI = 1S/C4H8O2.3O3S/c1-2-6-4-3-5-1;3*1-4(2)3/h1-4H2;;; InChIKey = VZBNWRDNLDRWOZ-UHFFFAOYSA-N (useful for effecting Beckmann rearrangements;8 sulfonation of alkenes11 and arenes16) Physical Data: mp 75 °C,2 but almost never isolated. Solubility: generated as a solution in dioxane, with or without other solvents. Preparative Methods: the Organic Synthesis procedure2 involves reaction of Sulfur Trioxide (as Sulfan B) with dioxane in 1,2-dichloroethane. The complex precipitates and is used immediately. An alternate procedure involves treatment of dioxane with ClSO3TMS,3 itself prepared by reaction of Chlorotrimethylsilane and Chlorosulfonic Acid.4 Handling, Storage, and Precautions: reacts vigorously with water, alcohols, etc. It has been reported to decompose violently upon standing at rt2 or upon heating to 75 °C.5 The chemistry is essentially that of SO3 with some attenuation in reactivity. Safety precautions in the handling of SO3, which can be an unexpectedly strong oxidant, should be followed.1c

Traditionally a single CD width parameter is expressed in a metrology measurement of an amplitude modulated waveform. The measurement is the result of a single and specific edge detection algorithm applied to the waveform. There is no distinction between scale and shape (profile). Feedback and feedforward use of metrology information requires such a distinction as well as some sense of how far to trust the data in making process decisions. Typical metrology waveforms are obtained from optical imaging (overlay, mask, end of line truncation), scanning mechanical probe, optical diffraction, ellipsometry and SEM tools. This system we describe separately determines shape and scale of linewidth metrology by combining an entire range of edge detection parameters in the space domain. It specifically is used to monitor scale and shape changes from a basic template derived from the process margin. It can also be used to determine what portion of the linewidth or profile has deviated from the template in a diagnostic sense. The method repeatedly measures all possible features from the 1D or 2D waveforms stored in memory. Derived values of characteristic features are determined from the string of data obtained from the edge detection parameters. (sidewall width and angle, footing, topping, space features, 2D roughness, inflection positions) First the data is analyzed to confirm that it is valid and supports the requirements of the technology and level. Only valid data of rated quality is utilized. The system output is a group of three values. Scale (nm), Quality Index (0-1), Descriptive Bin (Deviation of shape and scale denoted A-Z). The Quality Index is a weighted consideration of template deviation (Both shape and measure error). i.e. CD feature equals 0.23 micrometer, 0.67, F (footing) This paper describes our attempts to find ways of extracting the information needed to monitor the pattern transfer process from CD SEM waveforms. The basic idea however applies to all metrology waveforms that approximate the topographical contours of a feature. Multiple Parameter Characterization (MPC) in the space and frequency domain as well as whole, partial and derivative waveform correlation are the basic tools utilized for quality and shape determination. The core principle is that different physical features are more strongly expressed in different parts of the SEM intensity traces. Some of these physical features are more predictive of how the pattern transfer occurs than others. Modern linewidth metrology systems require that the distinction be made between scale and shape. Automated inspection systems require that this be carried out quickly and robustly for it to have any production impact. Metrologists have always made such distinctions in evaluating features by utilizing all manner of direct and indirect observation of the monitored process. Unfortunately the abilities of the metrologist are not yet available as a supported automated system running 24 X 7.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Critical dimension scanning electron microscope metrology attempts to relate the electron intensity signal of the SEM tool to the actual size and shape of the feature measured. This intensity signal is frequently visualized and manipulated as a profile or waveform. A measurement of the size of a futuro involves the extraction of edge positions from this waveform. Traditional line width metrology ignores much of the effect of the variation of the shape of the feature measured on the waveform to be analyzed. Deducing the shape of a feature from the waveform requires interpretation of the shape of the waveform. Analysis of the CD SEM intensity signal allows one to not only measure the specific width of a feature but it also allows a better estimate as to the actual shape of the feature. Both photo and etch production process drift can be monitored, resulting in improved process and quality control before gross failures in metrology occur.

Automated scanning electron microscopy tools are employed in semiconductor manufacturing to monitor the pattern-transfer process. Both feedback and feedforward information are used to control the process. The challenge for this nondestructive evaluation technique is not the instrumentation, but rather the intelligent use of the feedback and feedforward metrology inputs so that the process produces a product within specification with a minimal deviation because of in-time process drift correction.

The preparation of S-(−)-6-methyl-2-piperidinone from S-alanine and R-(−)-5-methyl-2-pyrrolidinone from S-glutamic acid and their conversion into S-2-methyl-1-azoniatricyclo[4.4.4.01,6]tetradecane (2a) and R-2-methyl-1-azoniatricyclo-[4.4.3.01,6]tridecane (2b) with enantiomeric excesses of 95 and 92% respectively are described. The use of these compounds as phase-transfer catalysts did not lead to significant asymmetric induction.

Oxidation of 1,3-oxathiolan-5-ones (1) gives acceptable yields of sulfoxides only when C4 is unsubstituted. Sulfoxides derived from 1,3-thiazolidine-4-ones (8) are easily prepared. Acid-catalyzed rearrangement in the presence of 1-alkenes or benzene leads to alkylation (arylation) at C5. Alkylation of 8c may be generally more effective than that of 1. An aldol condensation of 8c shows little stereoselectivity.

Alkylation of the D-camphor imine of tert -butyl glycinate with secondary allylic and benzylic halides affords products which have high stereochemical purity, particularly at the halogen displacement site.

The preparation of a series of vinyltriphenylphosphonium salts, all of which bear a substituent on the carbon attached to phosphorus, is described. Yields are generally poor unless a symmetrical secondary allylic halide can be used. The use of these salts in the preparation of substituted 2,5-dihydrothiophenes has been examined. In general, reaction times are increased and product yields decreased relative to the reactions of the unsubstituted salts previously reported. This result is ascribed to steric inhibition of the intramolecular Wittig reaction.

La trimethyl-2,2,4 oxathiolanne-1,3one-2 (A) est alkylee en 4 par des halogenures d'alkyle en presence de LDA/HMPT; la dimethyl-2,2,4 oxathiolanne-1,3one-2 (B) ne donne pas de produit d'alkylation. Les deux composes A et B donnent des produits d'aldolisation diastereoisomeres avec des aldehydes et cetones et des produits d'addition 1,2 ou 1,4 avec la cyclohexene-2one ou la butene-3one-2

Distillation of ω-carboxyalkyl lactams from soda-lime leads to the formation of bicyclic enamines or imines with concomitant loss of carbon dioxide and water. Monoamides of dicarboxylic acids afford cyclic ketones. A mechanistic rationale is presented and it is concluded that the reaction is a variant of the classical Ruzicka cyclization of dicarboxylic acids. The method allows the regiospecific formation of iminium salts of bicyclic nitrogen heterocycles.

The use of 3-carboxylated 2,5-dihydrothiophenes as the dienophilic component of the Diels–Alder reaction has been investigated. The yields are generally quite low. The formation of conjugated dienes that are aminated at an interior position of the conjugated chain by formation and thermal decomposition of 3-acetamido-2,5-dihydrothiophenes appears to be a viable route to these useful compounds. One example of the Diels–Alder reaction of 2-carboxylated diethyl vinylphosphonates is reported.

The rationale for considering 1-azoniapropellane salts as potential chiral phase-transfer catalysts is presented. The synthesis of two examples of these types of molecules is outlined and their efficacy in phase-transfer catalyzed reactions is established.

Vinylphosphonates 11, readily prepared from diethyl carbomethoxymethyl phosphonate (10) react with α-mercaptocarbonyl compounds to afford substituted 3-carbomethoxy-2,5-dihydrothiophenes in excellent yields. The scope of this synthesis is indicated and the use of the products in the synthesis of substituted 2-carboxy-1,3-butadienes is illustrated.

Regiospecific formation of 10-allyl-1-ketoquinolizidine (7) is achieved in high yield by a [2.3] sigmatropic rearrangement of N-allyl-1-ketoquinolizidinium bromide (6). Wolff–Kischner reduction of 7 affords 10-allylquinolizidine (8) contaminated by the 10-propyl and 10-ethynyl analogs in amounts which depend on the reaction conditions. The carbon-13 spectrum of 8 indicates a trans-fused ring system with an axial substituent at C-10.

The reaction of α-mercaptoaldehydes and ketones with 1,3-butadien-1-yltriphenylphosphonium salts (4) unexpectedly leads to 3-vinylthiophenes and triphenylphosphine. This result is attributed to the retardation of the usual Wittig cyclization reaction which allows the competing reaction to occur.

The complete carbon-13 nmr spectra of 16 alkylated 2,5-dihydrothiophenes and 10 sulfones derived from them are reported. No significant interactions between C-2 substituents and C-5 are noted and stereochemical determinations based on this γ effect are not possible. On oxidation to the sulfones, C-2 and C-5 are dramatically deshielded but C-3 and C-4 are shielded. A possible explanation for this effect is presented.

L'exces diastereoisomere est relie a la densite d'electrons π et aux effets steriques dans l'electrophile

The alkylation of the sodium, potassium, zinc, and zirconium enolates of the R-camphor imine of tert-butyl glycinate have been examined and the stereochemical results compared with those obtained with the lithium enolate. No difference was noted for the sodium enolate but inferior chemical yields and stereoselectivities were obtained with the potassium enolate, perhaps due to its increased ionic character. Substituting TMEDA for HMPA in these reactions led in all but one case to reduced stereoselectivities. The results support and are interpreted in terms of the π–metal association model previously proposed.

The preparation of 2-carboxylated-1,3-dienes from carbomethoxy vinylphosphonates and 2-mercaptocarbonyl compounds has been shown to give stereoisomeric mixtures. This may be due to the formation of stereoisomers of the intermediate 2,5-dihydrothiophenes and (or) to the occurrence of both modes of disrotatory sulfur dioxide elimination.

An improved synthesis of 1-azoniatricyclo[4.4.3.0 1,6 ]tridecane ( 2 ) and the preparation of the remaining member of the series, 1-azoniatricyclo[4.3.3.0 1,6 ]dodecane salts ( 3 ) have been achieved. Using a combination of 1 H (at 400 MHz) and 13 C NMR spectra has allowed the assignment of the signals in the well-resolved 1 H spectra. The results indicate that 1 exists in the all-chair form which undergoes racemization by ring inversion with a rate constant of 0.7 sec − and further that the counterion in these salts is restricted to associating with only one face of the tetrahedral N atom.

Alkylation of the (R)-camphor imine of tert-butyl glycinate with a variety of alkylating agents gave diastereoselectivities ranging from 0–100%. Simple alkyl halides larger than methyl give de's (diastereomeric excesses) of ca. 50% whereas those derived from allylic type systems afford de's of 75–100%. The results are best explained by invoking a transition state interaction between the π system of the alkylating agent and the imine which, for steric reasons, requires alkylation to occur from the pro-R face.

The crystal structures of 1-azoniatricyclo[4.4.4.01,6]tetradecane bromide (1) and 1-azoniatricyclo[4.4.3.01,6]tridecane bromide (2) are reported. Compound 1, C13H24NBr, crystallizes in space group P63/mmc with a = 8.383(2) Å, c = 10.092 Å, γ = 120°, Z = 2. Compound 2, C12H22NBr, crystallizes in space group P63/mmc with a = 8.283(2) Å, c = 10.046(2) Å, γ = 120°, Z = 2. The crystal structures of 1 and 2 are statistically disordered with both enantiomers occurring in the unit cell. Compound 2 is further disordered with the one five-membered ring and the two six-membered rings of the cation being averaged over the same site in the unit cell.The structures confirm the previously reported conclusions based on the 400 MHz nmr spectra of 1.