Academic literature on the topic 'TROSY NMR'

(-)-Ushikolide A 4, isolated from a culture broth of Streptomyces sp. IUK-102, showed powerful activity against murine splenic lymphocyte proliferation (IC50 = 70 nM). The most important player in the synthesis of 4 described ( J. Am. Chem. Soc. 2008, 130, 16190) by Barry M. Trost of Stanford University was the ProPhenol ligand 1. The precursor 2 was prepared by coupling the mesylate 7, the alkyne 12, and the aldehyde 13. The first role of catalyst 1 was in mediating the enantioselective coupling of commercial 5 with 6 to give, after saponification and CuCl decarboxylation, the mesylate 7. The preparation of 12 began with the Noyori hydrogenation of the ester 8 to the alcohol 9 in the expected high ee. Note that although this transformation was carried out at 1800 psi, such reductions proceed well and in similar ee at 60°C and 60 psi. Brown crotylation of the derived aldehyde 10 delivered 11, that was homologated to the alkyne 12. The third fragment 13 was prepared by chiral auxiliary directed aldol condensation. Combination of 12 with 13 was followed by Au-mediated cyclization, converting the internal alkyne of 14 to the spiroketal of 15. Pd-catalyzed coupling of 15 with 7 then led to 2 with high diastereocontrol. The aldol addition of the enolate of 17 to 18 proved elusive under the usual conditions, but with 30 mol % of the Zn catalyst 1 the reaction proceeded smoothly, to deliver 19 with high diastereocontrol. To complete the synthesis, hydroboration with 9-BBN was effected on the free carboxylic acid 3, and Pd-mediated coupling of the derived borane was carried out with the free iodo alcohol 2. As a result, the product hydroxy acid 20 could be taken directly to the subsequent macrolactonization.

The importance of the Etruscans does not simply lie in the painted tombs whose lively designs captivated D. H. Lawrence, nor in the puzzle of where their distinctive language originated, nor in the heavy imprint they left on early Rome. Theirs was the first civilization to emerge in the western Mediterranean under the impetus of the cultures of the eastern Mediterranean. Etruscan culture is sometimes derided as derivative, and the Etruscans have been labelled ‘artless barbarians’ by one of the most distinguished experts on Greek art; anything they produced that meets Greek standards is classified as the work of Greek artists, and the rest is discarded as proof of their artistic incompetence. Most, though, would find common cause with Lawrence in praising the vitality and expressiveness of their art even when it breaks with classical notions of taste or perfection. But what matters here is precisely the depth of the Greek and oriental imprint on Etruria, the westward spread of a variety of east Mediterranean cultures, and the building of close commercial ties between central Italy, rarely visited by the Mycenaeans, and both the Aegean and the Levant. This was part of a wider movement that also embraced, in different ways, Sardinia and Mediterranean Spain. With the rise of the Etruscans – the building of the first cities in Italy, apart from the very earliest Greek colonies, the creation of Etruscan sea power, the formation of trading links between central Italy and the Levant – the cultural geography of the Mediterranean underwent a lasting transformation. Highly complex urban societies developed along the shores of the western Mediterranean; there, the products of Phoenicia and the Aegean were in constant demand, and new artistic styles came into existence, marrying native traditions with those of the East. Along the new trade routes linking Etruria to the east came not just Greek and Phoenician merchants but the gods and goddesses of the Greeks and the Phoenicians, and it was the former (along with a full panoply of myths about Olympus, tales of Troy and legends of the heroes) that decisively conquered the minds of the peoples of central Italy.