共查询到20条相似文献,搜索用时 15 毫秒
1.
[structure: see text] Stereoselective total synthesis of scytophycin C, a marine 22-membered macrolide displaying potent activity against a variety of human carcinoma cell lines, has been reported in which the polypropionate structure bearing contiguous asymmetric centers was stereospecifically constructed by using new acyclic stereocontrol. This paper describes stereoselective syntheses of the C(1)-C(18) segment (Segment A) including a trans-disubstituted dihydropyran ring and the C(19)-C(31) segment (Segment B) having eight stereogenic centers. 相似文献
2.
The efficient construction of the C1-C13 segment of dolabelide B is described. A key element of the synthesis entails BITIP catalyzed asymmetric methallylation to establish the C7 stereocenter, which was then used to direct the stereoselective installation of the C9 and C11 centers through Evans reduction and 1,5-anti aldol condensation, respectively. 相似文献
3.
《Tetrahedron letters》1988,29(35):4481-4484
A synthesis of the C(1)-C(15) segment (4) of Tsukubaenolide (1) from Tri-O-acetyl-D-glucal and (S)-Pipecolinic acid methyl ester is described. 相似文献
4.
[reaction: see text] Employing enzymatic desymmetrization and resolution, respectively, the two aldehydes 8 and 20 were prepared. The precursor to aldehyde 8, meso-2,4-dimethylglutaric anhydride 3, could be obtained by base treatment of the diastereomeric mixture. Aldehyde 8 was extended to alkyne 10 by a Marshall reaction introducing four carbon atoms. Lithiation of the derived iodide 15 and trapping of the anion with amide 22 gave ketone 23. This compound led to the C10-C23 fragment 27 of dictyostatin. 相似文献
5.
《Tetrahedron letters》1987,28(27):3061-3064
A key subunit of aplasmomycin comprising C3-C10 of the symmetrical macrodiolide structure has been synthesized in optically pure form by two routes from (R)-(+)-pulegone. 相似文献
6.
[reaction: see text] A highly convergent asymmetric synthesis of the masked southern segment of the antimitotic agent disorazole A(1) involves a Sonogashira coupling between a C1'-C10' enyne and a suitably protected C11'-C19' vinyl iodide. The central E,Z,Z-triene moiety is masked as a more stable ynediene. 相似文献
7.
8.
[reaction: see text] Stereoselective syntheses of the C(1)-C(18) segment (segment A) and the C(19)-C(31) segment (segment B) are described in the preceding paper. This paper reports the key coupling reaction of both segments, 22-membered lactonization, and the crucial terminal amidation reaction culminating in the total synthesis of scytophycin C. 相似文献
9.
An enantioselective route for the synthesis of key fragment C1-C20 resident in microsclerodermins A and B is described. The route features deoxygenative rearrangement of an hydroxy-alkynoate and a highly enantio- and diastereo-controled iterative dihydroxylation as key reactions, starting from S-(−)-citronellol. 相似文献
10.
11.
A highly stereoselective synthesis of the C(1)-C(11) fragment 4 of peloruside A has been accomplished via a stereoselective double allylboration and an intramolecular epoxide opening to provide the functionally dense C(3)-C(11) segment 14. A glycolate aldol reaction was then employed to introduce the remaining stereocenters at C(2)-C(3). [reaction: see text] 相似文献
12.
The stereoselective synthesis of the C(8)-C(17) sub-unit (−)-5 of tedanolide (1), which involves iterative Evans aldol reactions as the key steps, is described. 相似文献
13.
Matthew Ball 《Tetrahedron letters》2004,45(47):8737-8740
A synthesis of the C(1)-C(16) fragment of the brysostatins has been developed. Key steps are the stereoselective copper(I) catalysed addition of allylmagnesium bromide to an alkynyl ester, a condensation of a βγ-unsaturated aldehyde with a ketophosphonate, and the formation of the B-ring under mild conditions by stereoselective intramolecular conjugate addition. 相似文献
14.
A highly stereoselective synthesis of the C10-C23 fragment of (-)-dictyostatin has been achieved using a Carreira alkynylation and a Marshall-Tamaru allenylzinc addition as key steps. 相似文献
15.
Mukund K. Gurjar Yakambram Pedduri C.V. Ramana Vedavati G. Puranik Rajesh G. Gonnade 《Tetrahedron letters》2004,45(2):387-390
Dihydroxylation of the glucose derived α,β-unsaturated lactones 6 and 13 was found to be on the α-face of the pyranolactone ring exclusively. The resulting dihydroxylated compound from 13 has been used in a synthesis of the lactone 4, which corresponds to C(1)-C(11) of peloruside A. 相似文献
16.
An efficient synthesis of the C1-C19 segment of aplyronine A is described. Stereoselective construction of the C14-C15 (E)-trisubstituted double bond and the C13 stereocenter was achieved by using an asymmetric Nozaki-Hiyama-Kishi coupling. 相似文献
17.
A convergent synthesis of the C1-C16 segment of goniodomin A, an actin-targeting marine polyether macrolide natural product, has been achieved via a 2-fold application of palladium-catalyzed organostannane-thioester coupling. 相似文献
18.
A stereoselective synthesis of the C(1)-C(12) segment of the potent cytotoxic macrolide, iriomoteolide 1a, has been accomplished. The key steps involve an enzymatic kinetic resolution of a β-hydroxy amide, a Pd-catalyzed cross-coupling to a substituted allylsilane, a highly regio- and stereoselective conjugate addition of lithium dimethylcopper to an α, β-acetylenic esters and an elaboration of the C(6)-C(7) trans-olefin geometry by a Julia-Kocienski olefination. 相似文献
19.
The challenging synthesis of a quaternary center within the highly oxygenated setting of tedanolide C can be performed via a Kiyooka aldol reaction. Here, the diastereomeric analog of tedanolide C with the configurations between C10 and C20 opposite compared to the proposed structure was chosen as the synthetic target. The tetra-substituted silyl ketene acetal provides the southern hemisphere of tedanolide C in useful selectivities, and the absolute configuration of the newly generated quaternary center was determined by NOE experiments of the corresponding acetonide. 相似文献