Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

• Mohan Mahesh,
• John A. Murphy,
• Franck LeStrat and
• Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

• the radical chemistry. One way to achieve clean termination of the radical process would be by providing a radical leaving group adjacent to the cyclised radical 19. Appropriate groups might be sulfide, sulfoxide and sulfonyl groups [64][65]. Accordingly, arenediazonium salts 31a–d were prepared

• like a sulfide, sulfoxide or sulfone is necessary for the self-termination of the 5-exo-trig radical cyclization reactions to avoid competing intermolecular radical side-reactions. The TDAE-mediated radical-based addition-elimination route for the construction of indole ring systems warranted anhydrous

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• the sodium enolate of 59 to afford the main structure 60. Oxidation of the sulfide 60 followed by thermal elimination and deprotection completed the total synthesis of solamin (57). The data of the synthetic 57 were identical to those of an authentic sample [38]. In their total synthesis of solamin

• alkylate the sodium enolate of lactone 15 to afford 70. Oxidation of the sulfide 70 followed by thermal elimination and finally removal of the two silyl protective groups gave solamin (57). But after careful comparison the configuration of the OH-group in C13 between the literature for isolation [38] and

• 298 with the propargylic alcohol 297 proceeded smoothly to produce the skeleton 299. The enyne functional group was reduced selectively and final global deprotection with BF3·Et2O in dimethyl sulfide afforded 294 as a colorless wax. The spectroscopic data for synthetic 294 (1H NMR, 13C NMR, IR, MS

Efficient 1,4-addition of α-substituted fluoro(phenylsulfonyl)methane derivatives to α,β-unsaturated compounds

• G. K. Surya Prakash,
• Xiaoming Zhao,
• Sujith Chacko,
• Fang Wang,
• Habiba Vaghoo and
• George A. Olah

Beilstein J. Org. Chem. 2008, 4, No. 17, doi:10.3762/bjoc.4.17

• . We first began with the preparation of nitro, cyano, ester, or acetyl-substituted (phenylsulfonyl)methanes from the corresponding (phenylthio)methane derivatives, the precursors of α-substituted fluoro(phenylsulfonyl)methane derivatives. Oxidation of (nitromethyl)(phenyl)sulfide with aqueous hydrogen

Analogues of amphibian alkaloids: total synthesis of (5R,8S,8aS)-(−)-8-methyl- 5-pentyloctahydroindolizine (8-epi-indolizidine 209B) and [(1S,4R,9aS)-(−)-4-pentyloctahydro- 2H-quinolizin- 1-yl]methanol

• Joseph P. Michael,
• Claudia Accone,
• Charles B. de Koning and
• Christiaan W. van der Westhuyzen

Beilstein J. Org. Chem. 2008, 4, No. 5, doi:10.1186/1860-5397-4-5

• -benzyl-1-phenylethylamine, was converted into the primary amine (−)-15 and thence in several steps into the thiolactam (+)-16. Eschenmoser sulfide contraction [22][23] with ethyl bromoacetate yielded the key enaminone intermediate (+)-17, chemoselective reduction of the saturated ester of which produced

• lactam (+)-26 was troublesome, giving at best a yield of 52% when performed with sodium hydride and tetrabutylammonium iodide in N,N-dimethylformamide. An effortless thionation of 26 with Lawesson's reagent in boiling toluene produced the thiolactam (+)-27 in 92% yield. Eschenmoser sulfide contraction

The use of chiral lithium amides in the desymmetrisation of N-trialkylsilyl dimethyl sulfoximines

• Matthew J. McGrath and
• Carsten Bolm

Beilstein J. Org. Chem. 2007, 3, No. 33, doi:10.1186/1860-5397-3-33

• , Entry 1), affording 2c in high yield and improved ee (86% yield, 70% ee, Table 2, Entry 2). When N-(diphenylmethylene)-toluenesulfonamide was used as electrophile the sulfoximine adduct 2d was obtained in low yield and ee (Table 2, Entry 3). In contrast, diphenyl disulfide gave sulfide 2e in accepee but

A convenient allylsilane- N-acyliminium route toward indolizidine and quinolizidine alkaloids

• Roland Remuson

Beilstein J. Org. Chem. 2007, 3, No. 32, doi:10.1186/1860-5397-3-32

• group followed by the simultaneous reduction of the two carbonyl groups of keto lactams 43a and 43b. Thus, treatment of 42a with ozone then with dimethyl sulfide afforded the expected keto lactam 43a in 91% yield. Ozonolysis of 42b led to keto lactam 43b in 63% yield. Reduction of 43a with lithium

Chiral trimethylsilylated C₂-symmetrical diamines as phosphorous derivatizing agents for the determination of the enantiomeric excess of chiral alcohols by ¹H NMR

• Anne-Sophie Chauvin and
• Alexandre Alexakis

Beilstein J. Org. Chem. 2006, 2, No. 6, doi:10.1186/1860-5397-2-6

• spectrum in the -0.4↔0.6 ppm region of 2-(2-isopropyl-5-methyl-cyclohexyloxy)-1,3-bis-trimethylsilanylmethyl-octahydro-benzo [1,3,2] diazaphosphole 2-sulfide. C2-diamines used in this study. Synthesis of diamines 1 and 2. Synthesis of diamine 3. 31P chemical shift differences Δδ (ppm) of some butan-2-ol P

Reagent controlled addition of chiral sulfur ylides to chiral aldehydes

• Varinder K. Aggarwal and
• Jie Bi

Beilstein J. Org. Chem. 2005, 1, No. 4, doi:10.1186/1860-5397-1-4

• clearly shown by sulfide 2 could be exploited in reactions with chiral aldehydes and to what extent it might dominate over substrate control (Scheme 2).[3] Again C1 stereochemistry should be controlled by ylide conformation, face selectivity, degree of reversibility in anti betaine formation, and is not

• the vicinal coupling constants (cis >trans). Assignment of the two trans diastereomers has been based on (i) the model for addition of the two enantiomers of the chiral sulfide to aldehydes and (ii) comparison of the H2-H3 coupling constants found for the major and minor diastereomers of the glycidic