Showing papers on "Total synthesis published in 1978"
175 citations
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TL;DR: In this article, the authors described direct total synthesis of 3-deoxyvitamin D2, vitamin D2 and vitamin D3, and showed that the original Z-allyl geometry of the phosphine oxides was completely preserved in the 5,6-double bond of the products, and the new (7,8-) double bond was formed with exclusive E-geometry.
Abstract: Direct total syntheses are described of 3-deoxyvitamin D2, vitamin D2, and vitamin D3. For the first, the lithio-derivative of (Z)-2-(2-methylenecyclohexylidene)ethyl(diphenyl)phosphine oxide and the Windaus–Grundmann ketone C19H32O were the reacting partners; for the second, the same ketone and the lithio-derivative of a protected form of (S)-(Z)-2-(5-hydroxy-2-methylenecyclohexylidene)ethyl(diphenyl)Phosphine oxide; and for the third, the same lithio-derivative and des-AB-cholestan-8-one. In these reactions, the original Z-allyl geometry of the phosphine oxides was completely preserved in the 5,6-double bond of the products, and the new (7,8-) double bond was formed with exclusive E-geometry.
84 citations
TL;DR: In this paper, the synthesis and chemistry of p-quinone methide ketals, prepared from monoketals 9a-c and a-tri-methylsilylamides or phosphoranes, is discussed within the context of the total synthesis of Amaryllidaceae alkaloid cherylline.
Abstract: The synthesis and chemistry of p-quinone methide ketals, prepared from p-quinone monoketals 9a-c and a-tri- methylsilylamides or phosphoranes, is discussed within the context of the total synthesis of Amaryllidaceae alkaloid cherylline (3).
79 citations
TL;DR: In this article, the naturally occurring Lycopodium alkaloid (+)-luciduline (1) has been synthesized from (R)-5-methyl-cyclohex-2-en-1-one (12) by a sequence of seven steps (s. Scheme 6) in 33% overall yield.
Abstract: The naturally occurring Lycopodium alkaloid (+)-luciduline (1) has been synthesized from (R)-5-methyl-cyclohex-2-en-1-one (12) by a sequence of seven steps (s. Scheme 6) in 33% overall yield. The key step 46 presumably involves a transient nitrone 5 which undergoes a highly regioselective intramolecular addition to a non-polarized olefinic bond.
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TL;DR: A simple synthesis of the title compounds, which is more than 10 steps shorter and an order of magnitude more efficient than our recent photochemical synthesis of chasmanine, is described in this paper.
Abstract: A simple synthesis of the title compounds, which is more than 10 steps shorter and an order of magnitude more efficient than our recent photochemical synthesis of chasmanine, is described. The main...
TL;DR: The total synthesis of the antibiotic malonomicin has been accomplished by a convergent synthesis in which the crucial step is a very mild coupling of the dipeptide sidechain to the 3position of the pyrrolidin-2,4-dione ring as mentioned in this paper.
TL;DR: In this paper, a biogenetic-type asymmetric synthesis of optically active galanthamine ((+)-4 and (-)-4) is described, and the synthesis of (-)-galanthamine from L-tyrosine via enantiomeric interconversion of narwedine derivative (12) is also described.
Abstract: A biogenetic-type asymmetric synthesis of optically active galanthamine ((+)-4 and (-)-4) is described. Norbelladine derivative (10), having C2 symmetry in the aromatic moiety of C6-C1-N part, was prepared from L-tyrosine, and was converted to narwedinetype enone (11) by oxidation and highly specific asymmetric cyclization. Phosphorylation of phenolic hydroxyl group followed by sodium borohydride reduction afforded 14 having galanthamine skeleton. N-Methylation followed by removal of the methoxycarbonyl and phosphate moieties afforded (+)-galanthamine ((+)-4). Formal total synthesis of (-)-galanthamine ((-)-4) from L-tyrosine via enantiomeric interconversion of narwedine derivative (12) is also described.