Tomoyuki Esumi

Chemistry and biological activities of Vibsane-type diterpenoids

This review focuses on the structural diversity, biological activities and synthesis of vibsane-type diterpenoids. Vibsane-type diterpenoids are considered to be rarely occurring natural products because they have been found exclusively in a few Viburnum species such as V. awabuki, V. odoratissimum, and V. suspensum. These diterpenoids are further classified into 11-membered ring, 7-membered ring, and rearranged (neovibsanin) types, and therefore, their chemical diversity forms a unique chemical library. We describe the absolute stereochemistry of the typical 11-membered ring vibsanins B and F, a variety of vibsane-type diterpenoids, the chemical correlations between the three subtypes, their biological activities, and the synthesis of vibsanin F and neovibsanin B.

A novel enantioselective synthesis of (+)-myriocin based on the chemistry of 1-trimethylsilylbuta-2,3-dienes

Abstract A synthesis of (+)-myriocin has been achieved in a highly stereoselective manner employing TiCl 4 catalyzed addition of 1-trimethylsilylbuta-2,3-diene to an aldehyde and Et 2 AlCl catalysed cyclization of an epoxytrichloroacetimidate for the construction of its α-substituted serine structure having three contiguous asymmetric centers.

Versatile enantiocontrolled synthesis of (+)-fostriecinElectronic supplementary information (ESI) available: experimental section. See http://www.rsc.org/suppdata/cc/b2/b209742g/

Fostriecin, a potent protein phosphatase inhibitor and antitumor agent, has been enantioselectively synthesized in naturally occurring form via a versatile route, which also allows one to secure all possible stereoisomeres of the C1-C13 fragment including the C11 stereocenter and the geometry of the delta 12-double bond.

Synthesis of viridiofungin A trimethyl ester and determination of the absolute structure of viridiofungin A

Abstract Four diastereoisomeric trimethyl esters of viridiofungin A, a member of novel family of aminoacyl alkyl citrate compounds, were synthesized in a highly stereoselective manner and the absolute configuration of natural viridiofungin A was determined to be 3 S ,4 S ,2′ S .

Synthesis of riccardin C and its seven analogues. Part 1: The role of their phenolic hydroxy groups as LXRα agonists

Riccardin C, a nuclear receptor LXRalpha selective agonist, is an 18-membered macrocyclic bisbibenzyl isolated from several liverworts. Synthesis of riccardin C and its seven O-methylated derivatives was accomplished. The synthetic sequence highlights an intramolecular Suzuki-Miyaura coupling in the formation of the 18-membered biaryl linkage present in riccardin C. The structure-activity relationship of these compounds suggests that all of the phenolic hydroxy groups present in riccardin C are essential for the activation of LXRalpha.

An enantio- and stereocontrolled synthesis of (−)-mycestericin E via cinchona alkaloid-catalyzed asymmetric Baylis–Hillman reaction

A new enantiocontrolled synthesis of a potent immunosuppressant(-)-mycestericin E has been accomplished by using cinchona alkaloid-catalyzed asymmetric Baylis-Hillman reaction of an aldehyde with 1,1,1,3,3,3-hexafluoroisopropyl acrylate and Lewis acid-promoted cyclisation of an epoxytrichloroacetimidate as the key steps.

Preparation of 2-Iodo-1,3-butadienes from 1-Trimethylsilyl-2,3-butadienes and their Functionalizations

Abstract Successive treatment of 1-trimethylsilyl-2,3-butadienes with iodine and tetra- n -butylammonium fluoride in the same flask affords 2-iodo-1,3-butadienes in good yields and their palladium-catalyzed carbonylation and alkynylation allows introduction of ester and alkynyl groups to the 2-position bearing an iodine atom leading to various 2,3-disubstituted 1,3-butadienes.

First enantiocontrolled formal synthesis of (+)-neovibsanin B, a neurotrophic diterpenoid.

An enantiocontrolled formal synthesis of (+)-neovibsanin B has been achieved by a sequence that applies an asymmetric 1,4-addition of (H(2)C=CH)(2)Cu(CN)Li(2) to trisubstituted alpha,beta-carboxylic acid derivative 1 to induce the chirality at the C-11 all-carbon quaternary center. Together with a modified Negishi cyclic carbopalladation-carbonylative esterification tandem reaction for constructing the A-ring, the synthesis was completed.

Convergent synthesis of 1α,25-dihydroxy-2β-(3-hydroxypropoxy)vitamin D3 (ED-71)

Abstract A convergent and versatile synthesis of the potent vitamin D analog, 1α,25-dihydroxy-2β-(3-hydroxypropoxy)vitamin D 3 [ 1 ] (ED-71) is described.

Stereocontrolled synthesis of (+)-lycoperdic acid based on a palladium catalyzed reaction using a serine-derived organozinc reagent

An efficient stereocontrolled synthesis of (+)-lycoperdic acid has been achieved based on palladium catalyzed cross-coupling reaction of (Z)-1-(tert-butyldimethylsiloxy)-3-iodo-6-(p-methoxybenzyl)oxy-2-hexene with the organozinc reagent, prepared from N-Boc-β-iodoalanine methyl ester.