139 research outputs found
ChemInform Abstract: Gold‐Catalyzed Dearomative Spirocyclization of Aryl Alkynoate Esters.
No full textGold-Catalyzed Dearomative Spirocyclization of Aryl Alkynoate Esters
No full textAryl
alkynoate esters undergo gold-catalyzed spirocyclization under
mild conditions, affording spirolactones in high yields. This approach
obviates the need for stoichiometric halogenating reagents typically
employed for alkyne activation in related transformations. Water was
found to play a critical role in governing the product selectivity.
Anhydrous conditions lead selectively to coumarin products, as has
previously been observed for aryl alkynoate esters, while the addition
of 1 equiv of water leads selectively to spirocycle formation
Pd-Catalyzed Conjunctive Cross-Coupling between Grignard-Derived Boron “Ate” Complexes and C(sp<sup>2</sup>) Halides or Triflates: NaOTf as a Grignard Activator and Halide Scavenger
No full textBertrand d' Echaux et le journal de Héroard
No full textBiografía de Bertrand d' Echaux que nació en Baïgorry en 1556 ó 1557. Parte de su vida se relata en el "Journal de Jean Héroard sur l' enfance et la jeunesse de Louis XIII". Jean Héroar fue nombrado médico del hijo de Enrique IV que sería posteriormente Louis XIII, y se relatan todos los incidentes, costumbres, la educación del Delfín. Bertrand d' Echaux aparece en el diario varias veces, que son recogidas en el textoBiography of Bertrand d'Echaux, who was born in Baigorry in 1556 or 1557. Part of his life is reported in the "Journal de Jean Hroard sur l' enfance et la jeunesse de Louis XIII" (Diary of Jean Hroard on the childhood and youth of Louis XIII". Jean Hroard was the appointed physician of the Henry IV's son that was later to become King Louis XIII. The author reports on all the incidents, mores, and the education of the heir to the throne. Bertrand d' Echaux is mentioned in the diary on several occasions, which have been compiled in this articl
Catalytic Enantioselective Synthesis of β‑Allenyl Boronic Esters by Conjunctive Cross-Coupling with Propargylic Carbonates
No full textEnantioselective
conjunctive cross-coupling with propargylic carbonates
affords β-boryl allenes as the reaction product. The reaction
is found to proceed through the intermediacy of dimethoxyboronate
complexes that are generated in situ by a strain-induced
ligand exchange reaction
Pd-Catalyzed Conjunctive Cross-Coupling between Grignard-Derived Boron “Ate” Complexes and C(sp<sup>2</sup>) Halides or Triflates: NaOTf as a Grignard Activator and Halide Scavenger
No full textCatalytic enantioselective conjunctive
cross-couplings that employ
Grignard reagents are shown to furnish an array of nonracemic chiral
organoboronic esters in an efficient and highly selective fashion.
The utility of sodium triflate in facilitating this reaction is two-fold:
it enables “ate” complex formation and overcomes catalytic
inhibition by halide ions
Pd-Catalyzed Conjunctive Cross-Coupling between Grignard-Derived Boron “Ate” Complexes and C(sp<sup>2</sup>) Halides or Triflates: NaOTf as a Grignard Activator and Halide Scavenger
No full textCatalytic enantioselective conjunctive
cross-couplings that employ
Grignard reagents are shown to furnish an array of nonracemic chiral
organoboronic esters in an efficient and highly selective fashion.
The utility of sodium triflate in facilitating this reaction is two-fold:
it enables “ate” complex formation and overcomes catalytic
inhibition by halide ions
Studies in scientometrics II. The relation between source author and cited author populations
No full textUma sequência anual de Citation Indexes mantém um padrão de comportamento em muito semelhante a uma sequência de Source Indexes. Cinco anos do Source Index (1964-1968) foram considerados como suficientes para distinguir, entre os autores, as classes de transientes e permanentes, e três anos do Citation Index (1966-1968) para identificar referências a autores iniciando publicação no começo do período. O arquivo listou 640 autores, dos quais 381 estavam incluídos nos cinco Source Indexes e 442 nos três Citation Indexes, sendo 183 nomes comuns a ambas categorias de índices. Dos autores transientes que aparecem apenas em um único Source Index, 71% não são citados, 19% são transitoriamente citados e somente 10% parecem ser permanentes em citação.Um autor transiente tem cerca de 30% de chance de ser citado em qualquer ano. Do núcleo de 22 autores permanentes que publicam nos cinco anos registrados,19 são também citados em todos os três anos. É importante notar que esses mesmos 19 autores são também aqueles que continuam não apenas por um períodode 5 anos mas pelo período de 7 anos registrados noestudo anterior. Os autores permanentes do Sourcetendem a ser permanentes também em citação. Um grupo de 259 autores que são citados não aparece entre os autores-fonte. Desses, 80% são transientes e 20%são permanentes. Com a edição de novos dados de citação e de características de grupos de autores não incluídos no Source, os grupos demográficos são distribuídos nas seguintes categorias: a) transientes, b) permanentes que não fazem parte do núcleo, c) permanentes integrantes ao núcleo, d) permanentes que continuam a ser citados embora não mais publiquem,e) antigos transientes e f) novos permanentes.AbstractA sequence of annual Citation Indexes behaves in very much the same way as the sequence of Source Indexes. Five years o f Source Index were regarded (1964-1968) as sufficient to distinguish the transient and continuant classes amongst the authors,and three years o f the Citation Index (1966-1968) to pick up references to authors commencing publication at the begining of the period. The file listed 640 authors of which 381 were in the five Source Indexes and 442 in the three Citation Indexes with 183 names being common to both sets of index.O f the transient authors who appear in only a single Source Index 71% are uncited, 19% are transiently cited and only 10% seem to be continuants in citation. A transient author has about 30% chance of being cited in any year. Of the core continuant authors who publish in ali five years of record, 19 of the 22 are also cited in all the three years. It\u27s worth noting that these 19 authors are also those who continue not merely for a five year span but for the seven years recorded in the previous study. Continuant source authors have astrong tendency to be continuants also in citation.A considerable group of 259 names in Citation Index do not appear amongst the source authors. Of the 259 names 80% are transiently cited and 20% are continuants. With the addition of new citation data and the characteristics oft he non-sourcegroups, not before detected, the demographic groups now become as: a) transients b) non-core continuants c) core continuants d) terminated continuants e) former transients f) newly recruited continuants
ChemInform Abstract: Facile One‐Pot Synthesis of Tetrahydroisoquinolines from Amino Acids via Hypochlorite‐Mediated Decarboxylation and Pictet—Spengler Condensation.
No full textStudies in scientometrics II. The relation between source author and cited author populations
No full textUma sequência anual de Citation Indexes mantém um padrão de comportamento em muito semelhante a uma sequência de Source Indexes. Cinco anos do Source Index (1964-1968) foram considerados como suficientes para distinguir, entre os autores, as classes de transientes e permanentes, e três anos do Citation Index (1966-1968) para identificar referências a autores iniciando publicação no começo do período. O arquivo listou 640 autores, dos quais 381 estavam incluídos nos cinco Source Indexes e 442 nos três Citation Indexes, sendo 183 nomes comuns a ambas categorias de índices. Dos autores transientes que aparecem apenas em um único Source Index, 71% não são citados, 19% são transitoriamente citados e somente 10% parecem ser permanentes em citação.Um autor transiente tem cerca de 30% de chance de ser citado em qualquer ano. Do núcleo de 22 autores permanentes que publicam nos cinco anos registrados,19 são também citados em todos os três anos. É importante notar que esses mesmos 19 autores são também aqueles que continuam não apenas por um períodode 5 anos mas pelo período de 7 anos registrados noestudo anterior. Os autores permanentes do Sourcetendem a ser permanentes também em citação. Um grupo de 259 autores que são citados não aparece entre os autores-fonte. Desses, 80% são transientes e 20%são permanentes. Com a edição de novos dados de citação e de características de grupos de autores não incluídos no Source, os grupos demográficos são distribuídos nas seguintes categorias: a) transientes, b) permanentes que não fazem parte do núcleo, c) permanentes integrantes ao núcleo, d) permanentes que continuam a ser citados embora não mais publiquem,e) antigos transientes e f) novos permanentes.AbstractA sequence of annual Citation Indexes behaves in very much the same way as the sequence of Source Indexes. Five years o f Source Index were regarded (1964-1968) as sufficient to distinguish the transient and continuant classes amongst the authors,and three years o f the Citation Index (1966-1968) to pick up references to authors commencing publication at the begining of the period. The file listed 640 authors of which 381 were in the five Source Indexes and 442 in the three Citation Indexes with 183 names being common to both sets of index.O f the transient authors who appear in only a single Source Index 71% are uncited, 19% are transiently cited and only 10% seem to be continuants in citation. A transient author has about 30% chance of being cited in any year. Of the core continuant authors who publish in ali five years of record, 19 of the 22 are also cited in all the three years. It's worth noting that these 19 authors are also those who continue not merely for a five year span but for the seven years recorded in the previous study. Continuant source authors have astrong tendency to be continuants also in citation.A considerable group of 259 names in Citation Index do not appear amongst the source authors. Of the 259 names 80% are transiently cited and 20% are continuants. With the addition of new citation data and the characteristics oft he non-sourcegroups, not before detected, the demographic groups now become as: a) transients b) non-core continuants c) core continuants d) terminated continuants e) former transients f) newly recruited continuants
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