@article{25d6f5c4d98a4b91a14fa5d6911dcec0,
title = "Enantiospecific total synthesis of (-)-allosamizoline, and aminocyclitol moiety of the insect chitinase inhibitor allosamidin",
abstract = "Total synthesis of (-)-allosamizoline (2), an aminocyclitol moiety of the insect chitinase inhibitor allosamidin (1) has been enantiospecifically synthesized from D-glucosamine by using an intramolecular cycloaddition of the nitrile oxide to an olefin as a key step.",
author = "Masaya Nakata and Seiji Akazawa and Shuji Kitamura and Kuniaki Tatsuta",
note = "Funding Information: Isoxazoline opening was a troublesomes tep. Of a variety of conditions including H2/Raney Ni-W4/AcOH/aq. dioxane5 and H2/Raney Ni-W4/B(OH)3/aq. dioxane,l2 ozonolytic cleavage (O3/O2,10 : 1 CH2C12-MeOH, -78 - -3O”C, 24 h)l3 of 10 furnished the B-hydroxy ketone 1110 [60 % yield basedo n the reacted1 0;m p 121.0-122.5{\textquoteright}C;[ aID -51” (c 0.53,C HCl3)l. Hydroxyl-directed reduction of 11 with Zn(BH4)2 in 1 : 1 THF-ether (O{\textquoteright}C, 3 h) afforded a single diol 1210 in quantitative yield [mp 102 - 103°C;[ aID +4{\textquoteright} (c 0 64, CHCl3)]. The stereochemistryo f this diol 12 was confirmed by its transformation to the cyclic carbamate1 310 [60 % overall yield; mp 192 - 193{\textquoteright}C; [o]D -7{\textquoteright} (c 0.39,C HC13)l by de-N-phthaloylahon (NH2NH2*H20,95 % aq. EtOH, 70°C,4 h) and benzyloxycarbonylation (BnOCOCl, Na2C03,l : 2 H20-CH2C12, OT, 1.5h ) followed by base treatment (NaH, THF, 25”C, 4 h). Desilylation (1% HCl-MeOH, 25{\textquoteright}C, 2.5 h) of 13 followed by acetylation (Ac20, pyridine, 25{\textquoteright}C, 18 h) gave the triacetate1 4lO in quantitative yield [[aID -25{\textquoteright} (c 0.41,C HCl3)]. This triacetate1 4 was treatedw ith 4 equiv of MeOTf in CH2C124aa t 25{\textquoteright}C for 5.5 h and the intermediary iminomethylether was treated with Me2NaHCI (TEA, CH2Cl2,25{\textquoteright}C, 2 h) in one pot to produce the allosamizoline triacetate. Finally, this was deacetylatedw ith 1M aq. HCl at 50°C for 4.5 h to give (-)-allosamizoline hydrochloride (2) in 80 % yield from 14. The lH and I3C NMR spectra and the optical rotation of the synthetic 2 were identical with the authentic data.3b Synthetic studies toward the total synthesis of allosamidin (1) are now in progress. Acknowledgment: We are grateful to the Institute of Microbial Chemistry for the generous support of our program. Financial support by the Ministry of Education, Science and Culture (Grant-in-Aid for Scientific Reseach) is gratefully acknowledged. We thank Professors A. Suzuki and A. Isogai (Tokyo University) for the IH and I3C NMR spectra of (-)-allosamizoline hydrochloride.",
year = "1991",
month = sep,
day = "23",
doi = "10.1016/S0040-4039(00)92386-4",
language = "English",
volume = "32",
pages = "5363--5366",
journal = "Tetrahedron Letters",
issn = "0040-4039",
publisher = "Elsevier Limited",
number = "39",
}