Stereoselective synthesis of the C1-C13 fragment of bistramide A

The C1-C13 fragment of bistramide A was prepared from 5-hexenoic acid in 15 linear steps and in 16% overall yield. The core 2,6-trans-tetrahydropyran ring was obtained via a kinetically controlled oxa-Michael cyclization from the corresponding chiral α,β-unsaturated hydroxyester. This precursor was prepared by using a diastereoselective alkylation reaction using Davies Superquat auxiliary and a diastereoselective Roush’s allylboration as key steps.     

Synthesis of the C1-C23 fragment of Spirastrellolide A

Synthesis of the C1-C23 fragment in spirastrellolide A is described, featuring a cyclic acetal-tethered RCM for stereoselective constructions of spiroketal, and a 1,3- anti aldol involving methyl ketone enolate and Mukaiyama conditions.     

Synthesis of the C1-C16 fragment of spirastrellolide A

Synthesis of the C1-C16 fragment of spirastrellolide A is described here featuring Sharpless asymmetric epoxidation, an acid promoted O-1,4-addition, and Mukaiyama 1,3-anti-aldol.     

Stereoselective synthesis of the C1-C13 fragment of 2,3-dihydrodorrigocin A

[Chemical reaction: see text] The first synthesis of the C1-C13 fragment of 2,3-dihydrodorrigocin A has been achieved from 6-bromohexanoic acid in 14 linear steps and an overall yield of 2%. The configurations of the stereogenic centers C8, C9, and C10 have been determined to be the same as for migrastatin.     

Synthesis of the C1-C9 fragment of callipeltoside-A

[reaction: see text] The C1-C9 fragment of callipeltoside (17) was prepared in 12 steps and 7.2% overall yield from bicyclic lactone (+)-4. Key steps include a stereoselective epoxidation and further regiocontrolled nucleophilic opening of the oxirane ring to install two vicinal stereocenters (C5 and C6), and the use of bis(trimethylsilyl) peroxide and a catalytic amount of Sn(IV) chloride for the chemoselective Baeyer-Villiger oxidation of unsaturated cyclopentanone 15.     

Synthesis of the C1-C16 fragment of the ajudazols

The synthesis of the C1-C16 framework of the ajudazols has been achieved taking advantage of a highly selective isobenzofuran oxidative rearrangement and a key Stille coupling to introduce the key C14-C15 bond.     

Synthesis of the C1-C12 fragment of amphidinolide T1

A synthesis of the C1-C12 fragment of amphidinolide T1 utilising Evans’ aldol, oxy-Michael and cross metathesis reactions as the key steps is described.     

Synthesis of macrolide antibiotics. 19. Synthesis of the C7-C13 fragment of erythronolide A

A stereocontrolled synthesis was carried out for the C⁷-C¹³ fragment of erythronolide A in 33 steps with an overall yield of 13% relative to starting levoglucosan.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 186–195, January, 1990.     

Synthesis of macrolide antibiotics Communication 4. Synthesis of the C11-C13 fragment of narbomycin

Conclusions The synthesis has been effected from 1,6-anhydro--D-glucopyranose (10 steps, overall yield 28.9%) of the C¹¹-C¹³ fragment of narbomycin, a polychiral 14-membered macrolide antiobiotic.For communication 3, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2572–2575, November, 1982.     

Synthesis of macrolide antibiotics. 22. Synthesis of the C8-C13 fragment of oleandonolide

The stereospecific synthesis of the C⁸-C¹³ fragment of oleandonolide was carried out in 15 steps with an overall yield of 4.48%.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2136–2142, September, 1991.     

Synthesis of macrolide antibiotics Communication 2. Synthesis of the C9-C13 fragment of erythronolides A and C and megalonolide

Conclusions The synthesis of the C⁹-C¹³ fragment of erythromycin A has been accomplished, starting from levoglusan (18 steps, 3.4%).For previous communications, see [1, 2].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2561–2568, November, 1982.     

Synthesis of the C23-C32 fragment of spirangien

The synthesis of the C23-C32 fragment of spirangien A is reported using Evans’ alkylation, Evans-Metternich aldol reaction and a substrate controlled stereoselective reduction.     

Stereoselective synthesis of the C1-C13 fragment of (+)-discodermolide using asymmetric allyltitanations

[reaction: see text] The synthesis of the C1-C13 fragment of (+)-discodermolide has been achieved. The configurations of the stereogenic centers have been controlled by enantioselective allyl- and crotyltitanations of aldehydes, and the Z configuration of the olefin at C8-C9 was controlled by a ring-closing metathesis.     

Enantioselective [4 + 2]-annulation of chiral crotylsilanes: application to the synthesis of a C1-C22 fragment of leucascandrolide A

[reaction: see text] The asymmetric synthesis of a C1-C22 fragment (2) of leucascandrolide A is described. Synthetic highlights include the construction of the C9-C22 pyran fragment using a formal [4 + 2]-annulation of a chiral organosilane. A diastereoselctive Mukaiyama aldol was used to introduce the C9 stereocenter and complete the assembly of the macrocycle's carbon skeleton.     

Synthesis of amphidinolide E C10-C26 fragment

The key C10-C26 fragment in a total synthesis of (-)-amphidinolide E has been prepared from an oxolane-containing C10-C17 segment (9, derived from L-glutamic acid) via a Julia-Kocienski reaction with aldehyde 3, followed by a Sharpless AD to obtain the desired diol. The C22-C26 fragment was installed by means of an efficient Suzuki-Molander coupling, with an organotrifluoroborate reagent (4, arising from a cross-metathesis reaction between a vinylboronate and 2-methyl-1,4-pentadiene).     

A convergent preparation of the C1-C13 fragment of amphotericin B from a single chiral precursor

A short, highly efficient, stereoconvergent synthesis of the polyolic chain, C1-C13, of the macrolide antibiotic amphotericin B is described. The key features of the synthesis are the use of a single chiral precursor for the establishment of the stereogenic centres in a short synthetic sequence, and the final alkyl lithium addition to the appropriate aldehyde, which showed high diastereoselectivity for the correct stereochemistry at the fifth stereogenic centre.     

Synthesis of the C1-C12 fragment of the tedanolides. Aldol-non-aldol aldol approach

The combination of highly stereoselective non-aldol aldol and aldol processes allows the preparation of the completely protected C1-C12 fragment 2 of the novel macrocyclic cytotoxic agent tedanolide 1.