SmI2-induced Cyclization Research Articles

New samarium diiodide-induced cyclizations

Samarium diiodide (SmI2) smoothly promotes the cyclizations of suitably substituted carbonyl compounds with styrene subunits leading to benzannulated cyclooctenes. The intramolecular samarium ketyl addition to arene or hetarene moieties enables a new, efficient, and highly stereoselective entry to dearomatized products such as hexahydronaphthalenes, steroid-like tetra- or pentacyclic compounds, or dihydroindole derivatives. The usefulness of the developed SmI2-induced cyclization method was demonstrated by the shortest formal total synthesis of the alkaloid strychnine.

ChemInform Abstract: SmI2‐Induced Cyclizations and Their Applications in Natural Product Synthesis

AbstractReview: 98 refs.

SmI 2-induced cyclization of ( E)- and ( Z)-β-alkoxyvinyl sulfones with aldehydes

SmI 2-induced reaction of ( E)- and (Z)-β-alkoxyvinyl sulfones onto an aldehyde function afforded 2,6- syn-2,3- trans- and 2,6- syn-2,3- cis-tetrahydropyran-3-ols, respectively, via stereoselective cyclization. This reaction was applied to the synthesis of 2-methyl-tetrahydropyran, corresponding to the N-ring of gymnocin-A, and 2- exo-methylene-tetrahydropyran, a key intermediate for convergent synthesis of polycyclic ethers based on the Suzuki–Miyaura reaction.

SmI 2-induced cyclization of optically active ( E)- and ( Z)-β-alkoxyvinyl sulfoxides with aldehydes

SmI 2-induced reaction of ( E)-β-alkoxyvinyl ( R)- and ( S)-sulfoxides with aldehydes effected a highly stereoselective intramolecular cyclization to give 2,6- anti-2,3- cis- and 2,6- syn-2,3- trans-tetrahydropyran-3-ols, respectively. The reaction of ( Z)-( R)-isomer gave 2,6- syn-2,3- cis-tetrahydropyran-3-ol and a ring-opened product, and that of ( Z)-( S)-isomer yielded many products.

Synthetic Studies on Maitotoxin. 2. Stereoselective Synthesis of the WXYZA′-Ring System

The stereoselective synthesis of the WXYZA'-ring system of maitotoxin has been accomplished via a linear synthetic approach, in which key reactions were SmI 2-induced cyclization of beta-alkoxyacrylate for the construction of the A'-, Y-, and X-rings and 6- endo cyclization of hydroxy vinylepoxide for that of the Z- and W-rings.

Studies on the efficient syntheses of the drug metabolites

This review summarizes our recent findings in the syntheses of drug metabolites. The metabolites of Grepafloxacin (1) and OPC-14117 (10) were prepared from the common intermediates (5) and (21), respectively. Moreover, treatment of 10 with a model P450 system led to a benzyl alcohol derivative (11) in one step. OPC-31260 (22) was efficiently N-dealkylated using several metalloporphyrins with oxidants to afford three metabolites (23-25). In addition, I succeeded in obtaining the metabolite (23) in high yield from N-oxide (26) not only as an oxygen donor but also as a substrate, there after, in the model P450 system. Optically active metabolites of OPC-29030 (27) were prepared by enzyme-catalyzed enantioselective transesterification of racemic sulfinyl metabolites. On the other hand, a chiral 1,1'-bi-2-naphthol derivative (38a) was found to be an efficient asymmetric acylating agent for a secondary alcohol (36) which is a valuable intermediate for preparing optically active metabolites of 22. Furthermore, metabolites (45) and (47) of OPC-21268 (44) were prepared using SmI2-induced cyclization and oxidative decarboxylation with Pb(OAc)4 as key steps, respectively.

ChemInform Abstract: Preparation of Medium‐ and Large‐Ring Lactones. SmI2‐Induced Cyclization of ω‐(α‐Bromoacyloxy) Aldehydes.

ChemInform Abstract: Preparation of Medium‐ and Large‐Ring Lactones. SmI₂‐Induced Cyclization of ω‐(α‐Bromoacyloxy) Aldehydes.

Preparation of medium- and large-ring lactones. SmI 2-induced cyclization of ω-(α-bromoacyloxy) aldehydes

ω-Bromoacetoxy- andω-(α:-bromopropionyloxy) aldehydes were cyclized by SmI 2 giving 8- to 14-membered ringβ-hydroxy lactones in excellent yields.