Systematic Strategy for the Synthesis of Cyanobacterin and Its Stereoisomers. 1. Asymmetric Total Synthesis of Dechloro-cyanobacterin and Its Enantiomer

Systematic Strategy for the Synthesis of Cyanobacterin and Its Stereoisomers. 2. Asymmetric Total Synthesis of the 2- and 3-Epimers of Dechloro-cyanobacterin

“…In the previous paper, 7) we have described the stereoselective total synthesis of dechloro derivative 2 as a model compound of 1 and its enantiomer 3. Both compounds were prepared from the same starting material 7 by using an asymmetric aldol reaction in the presence or absence of TiCl4, respectively producing non-Evans-type and Evans-type products as the key step.…”

“…Therefore, the starting material and basic plan for the synthesis of 4 and 5 were required to be similar to those in the previous report. 7) The retrosynthetic analysis of 4 is shown in Scheme 1. The stereochemistry at the C-3 position of 4 was achieved by chelation-controlled diastereoselective alkynylation of b-hydroxy ketone 6 before exposing to Ag ＋ -catalyzed exo-cyclization.…”

“…Each major product in this reaction (18 and 20) was identical with the minor isomer described in our previous report. 7) Similarly, each minor product, (19 and 21), corresponded to the objective compound in the previous paper. The IR, 1 H-and 13 C-NMR spectral date and speciˆc rotation of the corresponding compounds were identical with each other.…”

Phytogrowth‐ and photosynthesis‐inhibiting properties of nostoclide analogues

“…This is due in great part to resistance problems caused by severe selection pressure imposed by continuous application of products with the same mechanism of action 1, 2. Among the strategies used by the agrochemical industry to discover new products with new modes of action, the use of natural products continues to be of great importance, mainly as a source of new lead structures for chemical synthesis 3–6. In the allelopathy field there is increasing interest in understanding plant–plant and plant–micro‐organism interactions 2…”

Synthesis and Algicidal Activity of (+)-Cyanobacterin and Its Stereoisomer

“…The first total synthesis of racemic 1a was achieved by Jong et al 3) in 1984, and recently Haga et al 8,9) reported an asymmetric synthesis of both enantiomers of a dechlorinated analog of cyanobacterin and formal total synthesis of (+)-1a by employing Evans's asymmetric alkylation as the key step.…”