New methods and reagents in organic synthesis. 55. Total syntheses of patellamides B and C,cytotoxic cyclic peptides from a tunicate 1. Their proposed structures should be corrected.

Patellamides B and C, cytotoxic lipophilic cyclic peptides from a marine tunicate, with proposed structures have been synthesized by the use of diphenyl phosphorazidate(DPPA) and diethyl phosphorocyanidate(DEPC). Their physicochemical properties lead to reassign the structures of patellamides B and C on the bonding order.     

New methods and reagents in organic synthesis. 58. : A synthesis of patellamide a, a cytotoxic cyclic peptide from a tunicate. Revision of its proposed structure

The real structure of patellamide A, a cytotoxic lipophilic cyclic peptide from a marine tunicate, has been unambiguously determined by the synthesis of both its proposed and revised structures.     

New methods and reagents in organic synthesis. 51. A synthesis of ascidiacyclamide,a cytotoxic cyclic peptide from ascidian — determination of its absolute configuration

A first synthesis of ascidiacyclamide, a cytotoxic cyclic peptide from ascidian, has been achieved through the cyclodimerization with diphenyl phosphorazidate(DPPA), which has unambiguously determined the absolute configuration of ascidiacyclamide as $\text{1}$.     

New methods and reagents in organic synthesis. 65. A stereoselective synthesis of tilivalline

Tilivalline (1), a metabolite from Klebsiella, has been efficiently and stereoselectively synthesized from diphenyl phosphorazidate (DPPA), the 2-oxazoline 2, the L-proline derivative 5, and indole: the key step is a Mannich type intramolecular cyclization accompanied with simultaneous and completely stereoselective introduction of indole.     

New methods and reagents in organic synthesis. 62 trimethylsilyldiazomethane: A convenient reagent for the preparation of acylsilanes

The lithium salt of trimethylsilyldiazomethane smoothly reacts with alkyl halides to give α-trimethylsilyldiazoalkanes which are easily oxidized with m-chloroperbenzoic acid (m-CPBA), giving the corresponding acylsilanes (α-ketosilanes) in good yields.     

New methods and reagents in organic synthesis. 8. Trimethylsilyldiazomethane. A new,stable, and safe reagent for the classical arndt-eistert synthesis

Stable and safe trimethylsilyldiazomethane(TMSCHN₂) can be used efficiently for the Arndt-Eistert synthesis in place of highly toxic and explosive diazomethane.     

Novel Mg-organic reagents in organic synthesis. Cp2TiCl2 catalyzed intermolecular cyclomagnesiation of cyclic and acyclic 1,2-dienes using Grignard reagents

High-yield (>80%) catalytic intermolecular cyclomagnesiation of cyclic and acyclic allenes with the aid of Grignard reagents has been realized in the presence of Cp₂TiCl₂. The synthesized unsaturated bi- and tricyclic organomagnesium compounds (OMC) have been successfully converted in situ into thiophenes, unsaturated ketones, cyclic and acyclic hydrocarbons with high regio- and stereoselectivity.     

New methods and reagents in organic synthesis. 49. A highly efficient stereoselective synthesis of L-daunosamine through direct C-acylation using diphenyl phosphorazidate (DPPA)

L-Daunosamine, the carbohydrate component of a group of important anticancer anthracycline antibiotics, has been efficiently prepared from L-lactic acid in a completely stereoselective manner through direct C-acylation using diphenyl phosphorazidate (DPPA).     

New methods and reagents in organic synthesis, 40. Amination of aromatic and heteroaromatic organometallics using diphenyl phosphorazidate (DPPA)

Amination of aromatic and heteroaromatic organometallics is efficiently achieved by sequential treatment with diphenyl phosphorazidate (DPPA) and sodium bis(2-methoxyethoxy)aluminum hydride in a one-pot process.     

New methods and reagents in organic synthesis. 10. trimethylsilydiazomethane(TMSCHN2). A new,stable, and safe reagent for the homologation of ketones

Homologation of ketones can be achieved with trimethylsilyldiazomethane(TMSCHN₂) which is a stable and safe substitute for hazardous diazomethane.     

New methods and reagents in organic synthesis. 50. a stereoselective synthesis of a derivative of L-vancosamine,a carbohydrate component of the antibiotics vancomycin and sporaviridin

A derivative of L-vancosamine, a carbohydrate component of the antibiotics vancomycin and sporaviridin, has been prepared from L-lactic acid in a highly stereoselective manner.     

Total syntheses of makaluvamines A, B, C, D and E, cytotoxic pyrroloiminoquinone alkaloids isolated from marine sponge bearing inhibitory activities against topoisomerase II

Syntheses of makaluvamines A, B, C, D and E (1 – 5), new members of tetrahydropyrroloiminoquinone alkaloids, have been successfully carried out. Particularly, olefin introduction for makaluvamines B and E could be achieved by Pd - mediated and E₂ type methodologies.     

New methods and reagents in organic synthesis. 41. Lithium trimethylsilyldiazomethane. A new synthon for the preparation of pyrazoles from α,β-unsaturated nitriles

Lithium trimethylsilyldiazomethane reacts smoothly with various α,β-unsaturated nitriles to give 3(or 5)-trimethylsilylpyrazoles in good yields.     

New methods and reagents in organic synthesis, 24. A new synthesis of prumycin as an application of the direct c-acylation using diphenyl phosphorazidate (DPPA)

The 5-substituted 4-methoxycarbonyloxazole $\text{5}$ derived from L-serine derivative $\text{3}$ using diphenyl phosphorazidate (DPPA) has been converted to a 2,4-diaminosugar antibiotic, prumycin.     

Total synthesis of the didemnins - 2. Synthesis of didemnin A,B, C and prolyldidemnin A

Didemnin A, C, prolyldidemnin A and the highly cancerostatic, antiviral and immunosuppressive didemnin B have been prepared by deprotecting the benzyloxycarbonyl compound 5 and constructing the side chain that determines the biological properties.     

Total synthesis of the proposed structures of hyacinthacines C2, C3, and their C5-epimers

Synthesis and structural confirmation of highly oxygenated pyrrolizidine alkaloids, hyacinthacines C₂ [(1S,2R,3R,5R,7S,7aR)-3,5-hydroxymethyl-1,2,7-trihydroxypyrrolizidine], C₃[(1S,2R,3R,5S,7R,7aR)-3,5-hydroxymethyl-1,2,7-trihydroxypyrrolizidine], and their C5-epimers were achieved on the basis of the highly divergent method employing (S)-(−)-2-pyrrolidone-5-carboxylic acid as the starting material.     

A computational study on some viable targets for gas-phase synthesis of metal complexes of the cyclic (B6C)-2 and their bonding pattern

In this account, a detailed computational study is conducted to verify the geometric, energetic, and electronic properties of the planar cyclic (B 6C) (-2) (as the simplest carrier of hexacoordinate carbon) within some metal complexes. The [M(B 6C)] ((-)) (M = Li, Na, K) and [M(B 6C)] (M = Be, Mg, Ca) series are employed for this purpose. Relevant ab initio calculations at both DFT and post-HF levels vividly demonstrate that this dianion is stabilized considerably in the electric field generated by cations, whereas the geometrical and electronic properties of this ring remain almost intact in these complexes. The complementary topological analysis of charge densities confirms that cyclic (B 6C) (-2) within these complexes exhibits the same topological patterns as the naked dianion, thus confirming the presence of an unusual charge density distribution in this dianion. An electrostatic model is proposed that not only qualitatively but also quantitatively explains the observed computational trends in these complexes. This model successfully traces the polarization of the central carbon atom of the ring in the presence of a hard, multiply charged cation. To facilitate experimental detection, the photoelectron spectra of the [M(B 6C)] ((-)) (M = Li, Na, K) series are computed and the dominant features are extracted. Although considered species are not global minima on their potential energy hypersurfaces, their kinetic stabilities are verified and demonstrated unequivocally.     

Total synthesis and absolute stereochemistry of (+)-batzellaside B and its C8-epimer, a new class of piperidine alkaloids from the sponge Batzella sp.

The first total synthesis of (+)-batzellaside B and its C8-epimer was completed from a known l-arabinose-derived tribenzyl ether in 22 steps with overall yields of 3.9% and 5.4%, respectively. The absolute configuration of (+)-batzellaside B was unambiguously determined to be 1S,3S,4S,5R,8S by the Mosher analysis of a synthetic intermediate prepared through a separate route.     

Total syntheses of jaspamide (jasplakinolide) and geodiamolide A and B - 1. Stereoselective synthesis of (2S,4E,6R,8S)-8-hydroxy-2,4,6-trimethyl-4-nonenoicic acid1

The chiral aldehyde 7 was prepared by diastereoselective alkylation, subsequent 1,2- addition of isopropenylmagnesium bromide gave rise to a mixture (68:32) of the allylic alcohols 8 and 10 which was separated by recycling MPLC. Claisen rearrangement of the propionates of these alcohols under control of the enolate geometry finally yielded hydroxynonenoic acid 12b.