Geraniol, a monoterpene, and furan are structural motifs that exhibit antifouling activity. In this study, monoterpene-furan hybrid molecules with potentially enhanced antifouling activity were ...designed and synthesized. The nine synthetic hybrids showed antifouling activity against the cypris larvae of the barnacle
(
)
with EC
values of 1.65-4.70 μg mL
. This activity is higher than that of geraniol and the reference furan compound. This hybridization approach to increase antifouling activity is useful and can also be extended to other active structural units.
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•Reporting a stereocontolled synthesis of the macrolide core of neopeltlide, a cytotoxic macrolide.•The 2,6-disubstituted THP ring moiety was constructed by the intramolecular ...allylation of an α-acetoxy ether derivative.•A stereocontrolled synthesis of the macrolide core of neopeltlide was accomplished.
A stereoselective synthesis of the macrolactone core of neopeltolide is described. The tetrahydropyran moiety was constructed via the intramolecular allylation of an α-acetoxy ether. A late-stage macrolactonization provided a known synthetic intermediate of neopeltolide.
The xylem conducts water and minerals from the root to the shoot and provides mechanical strength to the plant body. The vascular precursor cells of the procambium differentiate to form continuous ...vascular strands, from which xylem and phloem cells are generated in the proper spatiotemporal pattern. Procambium formation and xylem differentiation are directed by auxin. In angiosperms, thermospermine, a structural isomer of spermine, suppresses xylem differentiation by limiting auxin signalling. However, the process of auxin-inducible xylem differentiation has not been fully elucidated and remains difficult to manipulate. Here, we found that an antagonist of spermidine can act as an inhibitor of thermospermine biosynthesis and results in excessive xylem differentiation, which is a phenocopy of a thermospermine-deficient mutant acaulis5 in Arabidopsis thaliana. We named this compound xylemin owing to its xylem-inducing effect. Application of a combination of xylemin and thermospermine to wild-type seedlings negates the effect of xylemin, whereas co-treatment with xylemin and a synthetic proauxin, which undergoes hydrolysis to release active auxin, has a synergistic inductive effect on xylem differentiation. Thus, xylemin may serve as a useful transformative chemical tool not only for the study of thermospermine function in various plant species but also for the control of xylem induction and woody biomass production.
The first total syntheses of sarcophytonolide H and the originally proposed and correct structures of isosarcophytonolide D have been achieved via transannular ring-closing metathesis (RCM). These ...total syntheses culminated in the stereostructural confirmation of sarcophytonolide H and the reassignment of isosarcophytonolide D, respectively. The antifouling activity of the synthetic sarcophytonolide H and its analogues was also evaluated.
Stereoselective and streamlined synthesis of the proposed C79–C104 fragment 2 of symbiodinolide (1), a polyol marine natural product with a molecular weight of 2860, was achieved. In the synthetic ...route, the proposed C79–C104 fragment 2 was synthesized by utilizing a Julia–Kocienski olefination and subsequent Sharpless asymmetric dihydroxylation as key transformations in a convergent manner. Detailed comparison of the 13C NMR chemical shifts between the natural product and the synthetic C79–C104 fragment 2 revealed that the stereostructure at the C91–C99 carbon chain moiety of symbiodinolide (1) should be reinvestigated.
Structural doubt: Stereoselective and streamlined synthesis of the C79–C104 fragment of symbiodinolide, a polyol marine natural product with a molecular weight of 2860, revealed that the stereochemistry of the C91–C99 carbon domain of this natural product needs to be reassigned (see scheme; Bn=benzyl, TBS=tert‐butyldimethylsilyl).
We have synthesized eight possible diastereoisomers 3 a–h of the C79–C97 fragment of symbiodinolide (1) in a stereodivergent manner by utilizing a dithiane addition to the aldehyde as a key step. ...Comparison of the 13C NMR chemical shifts of the natural product 1 and the synthetic products 3 a–h indicated that the relative stereostructure of this fragment in symbiodinolide (1) is that represented in 3 a or f. We have stereodivergently synthesized eight possible diastereoisomers of the C94–C104 fragment 4 a–h, and we have compared their 13C NMR chemical shifts with those of the natural product, which established the relative stereochemistry of this fragment to be that described in diastereoisomers 4 a or e. By combining the stereostructural outcomes of the C79–C97 and C94–C104 fragments, we have proposed four candidate compounds of the C79–C104 fragment 2 a–d. We also synthesized diastereoisomers 2 a and b (2 a in the preceding article; Chem. Eur. J. 2015, DOI: 10.1002/chem.201503880) by a Julia–Kocienski olefination and diastereoisomers 2 c and d by a Wittig reaction. By comparing the 13C NMR chemical shifts of natural symbiodinolide (1) with those of the synthetic products 2 a–d, we have reassigned the stereostructure of the C79–C104 fragment of natural product 1 to be that depicted in diastereoisomer 2 b.
Structural revision: Stereodivergent synthesis of eight possible diastereoisomers that correspond to the C79–C97 and C94–C104 fragments of symbiodinolide has been carried out, which resulted in the proposal of two candidate stereostructures, respectively. Subsequently, the synthesis of the four possible diastereoisomers of the C79–C104 fragment and comparison of their 13C NMR data with those of the natural product has allowed stereostructural revision of this fragment of symbiodinolide (see figure).
Stereoselective and parallel total syntheses of two possible diastereomers of (+)-sarcophytonolide C have been accomplished. Macrolactonization and transannular ring-closing metathesis (RCM) were the ...key transformations. Detailed comparisons of their 1H and 13C NMR data and specific rotation with those of the natural product allowed the absolute configuration of (+)-sarcophytonolide C to be determined.
Convergent synthesis of the EFGH ring segment of ciguatoxin CTX3C was investigated by using the intramolecular allylation of an α-chloroacetoxy ether and/or O,S-acetal, and subsequent ring-closing ...metathesis. A new method for the preparation of γ-alkoxyallylstannane is also described.
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Strategies for the synthesis of polycyclic ethers based on intramolecular allylations are overviewed. The intramolecular condensation of allylic stannanes and aldehydes is a powerful tool for the ...synthesis of oxepane derivatives. The reaction is successfully applied to the iterative total synthesis of hemibrevetoxin B (2). Further, the intramolecular allylation of α-acetoxy ethers provides an efficient method for the convergent synthesis of polycyclic ethers. The usefulness of the latter strategy is demonstrated in the convergent total synthesis of gambierol (4).
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