Enantiospecific synthesis of [2.2]paracyclophane- 4-thiol and derivatives

• Gareth J. Rowlands and
• Richard J. Seacome

Beilstein J. Org. Chem. 2009, 5, No. 9, doi:10.3762/bjoc.5.9

• of enantiomerically pure 4-hydroxy[2.2]paracyclophane or application of our own sulfoxide-metal exchange protocol [31] would permit enantiospecific variants of either route, but neither has been reported. An elegant entry to a variety of racemic alkyl sulfides and sulfoxides by an SEAr reaction

• developing a ‘tool-box’ for the synthesis of enantiomerically enriched [2.2]paracyclophane derivatives based on the chemistry of [2.2]paracyclophane sulfoxides [15][31][32][33]. This methodology has allowed us to develop routes to enantiomerically pure 4-monosubstituted [2.2]paracyclophanes [31] along with a

Synthesis of methylenebisamides using CC- or DCMT- activated DMSO

• Qiang Wang,
• Lili Sun,
• Yu Jiang and
• Chunbao Li

Beilstein J. Org. Chem. 2008, 4, No. 51, doi:10.3762/bjoc.4.51

• amides can be aromatic or aliphatic. The operation is simple and the reagents are inexpensive. Keywords: amides; condensation; DMSO; methylenebisamides; 2,4,6-trichloro[1,3,5]triazine; Introduction Sulfoxides are activated by electrophiles to produce reactive sulfonium salts. These electrophiles

• ], hexamethylenetetramine [21] or activated DMSO [6], or by the reaction of nitriles with formaldehyde [22] or activated sulfoxides [23]. However, each method has certain limitations with regards to scope and reaction conditions, for example, longer reaction time [20], lower yield [6], purification problems [21][23] and

Asymmetric synthesis of biaryl atropisomers by dynamic resolution on condensation of biaryl aldehydes with (−)-ephedrine or a proline- derived diamine

• Ann Bracegirdle,
• Jonathan Clayden and
• Lai Wah Lai

Beilstein J. Org. Chem. 2008, 4, No. 47, doi:10.3762/bjoc.4.47

• imidazolidines [25][27], ephedrine-derived oxazolidines [26][27], and, most extensively, sulfoxides [16][29][30][31]. These perform well when a powerful electronic or steric bias is evident about the atropisomeric bond over which control is applied [32], and in the case of atropisomeric amides have offered

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

• aryl-alkylsulfoximines are generally prepared by resolution with camphorsulfonic acid but this method is not applicable to dialkyl sulfoximines. [5][6][7] Imination of enantioenriched sulfoxides and derivatisation of sulfoximines with enantiomerically pure amino acid derivatives also provide

• enantioenriched S-chiral sulfoximines but both methods lack generality due to the limited availability of the appropriate chiral sulfoxides and the limited scope for cleavage of the chiral auxiliary in the latter process. [6][7][8][9][10][11][12][13][14][15] Selective substitution of one of the enantiotopic

• TMSCl quenching when sulfoximine 1b was first lithiated by treatment with n-BuLi followed by addition of a solution of (S,S)-bis-N,N-(1-phenylethyl)amine and lithium chloride (Scheme 5). In an analogous reaction, enantioenriched lithiated sulfoxides racemised via a reversible disproportionation to the