Organocatalytic Asymmetric α-Chlorination of 1,3-Dicarbonyl Compounds Catalyzed by 2-Aminobenzimidazole Derivatives

Bifunctional chiral 2-aminobenzimidazole derivatives 1 and 2 catalyze the enantioselective stereodivergent α-chlorination of β-ketoesters and 1,3-diketone derivatives with up to 50% ee using N-chlorosuccinimide (NCS) or 2,3,4,4,5,6-hexachloro-2,5-cyclohexadien-1-one as electrophilic chlorine sources.

Letter from S. Brown to William Tudor,

One letter thanking Tudor for sending Brown a memoir of the late William Tudor.

(Table 1) Granulometry, soil pH, carbonate content and color description of soil profiles obtained in Xinghai, Tibet

Large parts of the eastern half of the Tibetan Plateau are covered between (3,500) 4,000 and nearly 6,000 m a.s.l. by alpine sedge mats (key species Kobresia pygmea), which attain an extension of ca. 450,000 km**2. It is considered to be the world's largest alpine ecosystem. Moreover, there exist isolated (relic) forests in the same area up to an altitude of 4,700 m a.s.l. mainly consisting of juniper (Juniperus) and spruce (Picea). Large parts of the Kobresia ecosystem are expected to be a grazing-resistant replacement formation, replacing forests and grass-dominated plant communities due to human and/or climatic impact. Recently, a research project was launched to increase knowledge about the properties and genesis of these forests and sedge mats (Present-day dynamics and Holocene landscape history of fragmented forest biocoenoses in Tibet; headed by G. Miehe, Marburg).

(Table 1) Age determination of sediment cores of the Labrador Sea

A close look at the sedimentology of Heinrich event 4 from the northwest Labrador Sea indicates that an extended ice margin, perhaps greater than before Heinrich events 1 or 2 (H-1 and H-2), existed in the Hudson Strait region pre-Heinrich event 4 (H-4) and, that on the basis of characteristics of the sediment unit, Heinrich event-4 was different than Heinrich events 1 or 2 (i.e., larger ice sheet collapse(?), longer duration(?), "dirtier" icebergs(?)). Other data from across the southern and eastern margin of the Laurentide Ice Sheet, as well as Greenland and the North Atlantic, support this interpretation, possibly indicating a relative mid-Wisconsin glacial maximum pre-Heinrich event 4. Many of these data also indicate that Heinrich event 4 (35 ka) resulted in serious climatic and oceanographic reorganizations. We suggest that Heinrich event 4 gutted the Hudson Strait, leaving it devoid of ice for Heinrich event 3. We further hypothesize that Heinrich event 3 did not originate from axial ice transport along the Hudson Strait; thus Heinrich event 3 may be more analogous to the proposed northward advancing ice from Ungava Bay during Heinrich event 0 than to the more typical down-the-strait flow during H-1, H-2, and H-4. Consequently, the climatic and oceanographic impacts resulting from Heinrich events are highly susceptible to the type, origin, and magnitude of ice sheet collapse, something which varied per Heinrich event during the last glacial period.

[Calligraphic specimen, 1206, i.e. 1791 or 1792].

Exquisite album of calligraphy (muraqqaʻ / murakkaa) employing ḥadīth of the Prophet executed by the celebrated Ottoman calligrapher Mahmud Celâleddin Efendi (d.1829) in imitation of a model executed by the master calligrapher Hafız Osman Efendi (d.1698).

Ausführliche Abhandlung der römischen Alterthümer /

Includes indexes and errata.

Naẓm al-Jamīʻ al-ṣaghīr, [late 15th century?].

Fine copy of Abū Naṣr al-Farāḥī's (d.1242) versification of al-Jamīʻ al-ṣaghīr fī al-furūʻ, the well-known legal treatise by Muḥammad ibn al-Ḥasan al-Shaybānī (d.804). Excerpts from Kashf al-ẓunūn addressing these two works appear on leaf affixed to 'title page' (p.5).

A treatise on the eye, the manner and phaenomena of vision. In two volumes /

Mode of access: Internet.

Clavis Homerica, sive Lexicon vocabulorum omnium, quae in Homeri Iliade et potissima parte Odysseae continentur : cum indice locupletissimo necnon de dialectis et figuris appendice : quibus accessere varia elogia seu testimonia de Homero : etiam Michaelis Apostolii Proverbia Graeco-Latina.

Dunbar's "Rules, &c. of Homer's versification," in English: p. [v]-vii.

A General history of New England, from the discovery to MDCLXXX /

Mode of access: Internet.

Dramatic works of William Shakspeare, with a life of the poet and notes, original and selected.

v.2. Midsummer-night's dream. Love's labor's lost. Merchant of Venice. As y@u like it. All's well that ends well. Taming of the shrew.--v.3. Winter's tale. Comedy of errors. Macbeth. King John. King Richard the second. King Henry the fourth, pt. 1st.--v.4. King Henry the fourth, pt. 2d. King Henry the fifth. King Henry the sixth, pt. 1st - 3d.--v.5. King Richard the third. King Henry the eighth. Troilus and Cressida. Timon of Athens. Coriolanus.--v.7. King Lear. Romeo and Juliet. Hamlet, prince of Denmark. Othello, the Moor of Venice.

The Two Americas : Their complete history, from the earliest discoveries to the present day /

Earlier editions appeared under title: The People's history of America.

The Dabistan, or, School of manners /

Includes index.

Œuvres, traduites en français avec le texte et des notes,

Mode of access: Internet.

Ellis's husbandry, abridged and methodized: comprehending the most useful articles of practical agriculture.

Goldsmiths'-Kress no. 10859.2-1, suppl.