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-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 the C1-C13 fragment of leucascandrolide A

[reaction: see text] The synthesis of the C1-C13 fragment 3 of leucascandrolide A has been completed utilizing a stereoselective and regioselective reductive cleavage of a highly functionalized spiroketal to incorporate the cis-2,6-disubstituted tetrahydropyan. The spiroketal was constructed by addition of a lithiated pyrone 5 to aldehyde 6.     

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-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.     

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 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).     

Synthesis of the C15-C23 fragment of dictyostatin using a highly stereoselective Carreira alkynylation

A straightforward synthesis of the C15-C23 fragment of dictyostatin has been achieved by a highly stereoselective Carreira alkynylation between alkyne 1 and aldehyde 2, followed by three chemoselective reductions.     

Total synthesis of FR901464: second generation

FR901464, a potent cell cycle inhibitor, was synthesized in a convergent manner using natural chiral pool, l-threonine, ethyl (S)-lactate and 2-deoxy-d-glucose as starting materials.     

Synthesis of the C1-C16 fragment of ionomycin using a neutral (eta3-allyl)iron complex

Key steps in the synthesis of the C1-C16 polyketide fragment of ionomycin were the nucleophilic addition of an organocuprate to a neutral (eta3-allyl)iron complex and the construction of a beta-diketone moiety by the Rh-catalysed rearrangement of an alpha-diazo-beta-hydroxyketone.     

Synthesis of a C(1)-C(14)-containing fragment of callipeltoside A

[formula: see text] A C(1)-C(14)-containing fragment of callipeltoside A (1, Scheme 1) was synthesized efficiently via a dianion aldol coupling reaction between aldehyde 2 and ketoester 3. A surprising lack of reactivity between the alkenes in 13 and the Grubbs initiator 15 was encountered. An equally surprising rate acceleration of the reaction between 15 and allylic alcohols (alk-1-en-3-ols) as well as their subsequent cleavage to methyl ketones was discovered. In situ 1H NMR analysis has proven to be a very useful tool for monitoring RCM reactions of complex substrates such as 13.     

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.     

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 the C16-C35 fragment of integramycin using olefin hydroesterification as a linchpin reaction

[reaction: see text] The spiroketal unit of the HIV-integrase inhibitor integramycin has been prepared in an efficient and convergent manner. Key steps in this sequence include the use of ruthenium-mediated hydroesterification reactions of homoallylic alcohols and silyl ethers, and a C,O-dianionic addition into a lactone provides the spiroketal while minimizing protecting group manipulations.     

Synthesis of the C1-C12 fragment of iriomoteolide 1a by sequential catalytic asymmetric vinylogous aldol reactions

An efficient synthesis of the C1-C12 fragment of iriomoteolide 1a has been accomplished via sequential application of two catalytic, asymmetric, vinylogous aldol reactions: a catalytic vinylogous aldol reaction was used to enantioselectively introduce the C5-C8 segment, and a second catalytic vinylogous aldol reaction was used to install the remaining two stereocenters and a stereodefined alkene in the form of an alpha,beta-unsaturated delta-lactone in one step.     

Synthesis of the C21-C34 fragment of antascomicin B

The C21-C34 fragment of the potent FKBP12-binding macrolide antascomicin B was prepared using Ireland-Claisen and allylic diazene rearrangements to establish the C26/C27 and the C23 stereocenters, respectively. Directed hydrogenation installed the C29 β-configuration. The fragment possesses 7 of the 11 fixed stereocenters contained in the natural product.     

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.