An asymmetric synthesis of all stereoisomers of piclavines A1-4 using an iterative asymmetric dihydroxylation

• Yukako Saito,
• Naoki Okamoto and
• Hiroki Takahata

Beilstein J. Org. Chem. 2007, 3, No. 37, doi:10.1186/1860-5397-3-37

• ])-16 in 94%. It is impossible to utilize hydrogenolysis due to reactivity of the acetylene unit. Indeed, the N-protecting group exchange of benzyloxycarbonyl (Cbz) for 2,2,2-trichloroethoxycarbonyl (Troc) in 17 was examined. The use of basic reagents such as Ba(OH)2[11] and KOH[12] failed to afford

Flexible synthesis of poison- frog alkaloids of the 5,8-disubstituted indolizidine- class. II: Synthesis of (-)-209B, (-)-231C, (-)-233D, (-)-235B", (-)-221I, and an epimer of 193E and pharmacological effects at neuronal nicotinic acetylcholine receptors

• Soushi Kobayashi,
• Naoki Toyooka,
• Dejun Zhou,
• Hiroshi Tsuneki,
• Tsutomu Wada,
• Toshiyasu Sasaoka,
• Hideki Sakai,
• Hideo Nemoto,
• H. Martin Garraffo,
• Thomas F. Spande and
• John W. Daly

Beilstein J. Org. Chem. 2007, 3, No. 30, doi:10.1186/1860-5397-3-30

• the resulting aldehyde under Stork's conditions [11] provided the Z-iodoolefin 5 in a highly stereoselective manner. The Sonogashira coupling reaction [12] of 5 with TMS-acetylene followed by cleavage of the trimethylsilyl group with K2CO3 afforded (-)-231C. Although the rotation of the natural

Flexible synthetic routes to poison- frog alkaloids of the 5,8-disubstituted indolizidine- class I: synthesis of common lactam chiral building blocks and application to the synthesis of (-)-203A, (-)-205A, and (-)-219F

• Naoki Toyooka,
• Dejun Zhou,
• Hideo Nemoto,
• H. Martin Garraffo,
• Thomas F. Spande and
• John W. Daly

Beilstein J. Org. Chem. 2007, 3, No. 29, doi:10.1186/1860-5397-3-29

• reaction of the resulting aldehyde under Stork's reaction conditions, [25] gave the olefin. Purification by silica gel column chromatography afforded pure 15 in 60% isolated yield. The coupling reaction of 15 with TMS-acetylene under Sonogashira's conditions [26] gave rise to the product 16. Finally

Allylsilanes in the synthesis of three to seven membered rings: the silylcuprate strategy

• Asunción Barbero,
• Francisco J. Pulido and
• M. Carmen Sañudo

Beilstein J. Org. Chem. 2007, 3, No. 16, doi:10.1186/1860-5397-3-16

• key step is the syn addition of the tin cuprate to the acetylene, which controls the cis stereochemistry required for cyclization. [23] Seven Membered Carbocycles The use of nitriles and imines as electrophiles in the silylcupration of allene provides new alternatives for carbocyclization. Recently

Trapping evidence for the thermal cyclization of di-(o-acetylphenyl)acetylene to 3,3'-dimethyl- 1,1'-biisobenzofuran

• Charles P. Casey,
• Neil A. Strotman and
• Ilia A. Guzei

Beilstein J. Org. Chem. 2005, 1, No. 18, doi:10.1186/1860-5397-1-18

• Charles P. Casey Neil A. Strotman Ilia A. Guzei University of Wisconsin-Madison, Madison, WI 53706 10.1186/1860-5397-1-18 Abstract The reaction of di-(o-acetylphenyl)acetylene (1) with excess dimethyl acetylenedicarboxylate (DMAD) produced bis-DMAD adducts meso-3 and rac-3. This transformation is

• of the alkyne di-(o-acetylphenyl)acetylene (1) (Scheme 2). The addition of alkyne 1 to a solution of Cp(CO)2Re(THF) produced Cp(CO)2Re[η2-(di-(o-acetylphenyl)acetylene)] (2), which was detected by 1H NMR spectroscopy [δ 5.60 (Cp), 2.25 (Me)] (Scheme 2). However, we were unable to isolate 2. In the

• ] (Scheme 4) and to the related photoinduced bicyclization observed by Nakatani and Saito[9] (Scheme 5). Since suspected intermediate A proved too reactive to isolate, we sought to trap it with DMAD through Diels-Alder reactions with the isobenzofuran units. Acetylene 1 was dissolved in neat DMAD and the