5709-99-9Relevant academic research and scientific papers
Enantioselective synthesis of chiral sulfones by ir-catalyzed asymmetric hydrogenation: A facile approach to the preparation of chiral allylic and homoallylic compounds
Zhou, Taigang,Peters, Byron,Maldonado, Matias F.,Govender, Thavendran,Andersson, Pher G.
, p. 13592 - 13595 (2012/10/08)
A highly efficient and enantioselective Ir-catalyzed hydrogenation of unsaturated sulfones was developed. Chiral cyclic and acyclic sulfones were produced in excellent enantioselectivities (up to 98% ee). Coupled with the Ramberg-Baecklund rearrangement, this reaction offers a novel route to chiral allylic and homoallylic compounds in excellent enantioselectivities (up to 97% ee) and high yields (up to 94%).
Asymmetric diels-alder reactions of α,β-unsaturated aldehydes catalyzed by a diarylprolinol silyl ether salt in the presence of water
Hayashi, Yujiro,Samanta, Sampak,Gotoh, Hiroaki,Ishikawa, Hayato
supporting information; experimental part, p. 6634 - 6637 (2009/03/12)
(Chemical Equation Presented) Water, water, everywhere: The title reaction predominantly affords the exo isomer with excellent enantioselectivity (see scheme; TMS=trimethylsilyl). The synthesis can be carried out without organic solvents and provides the products by distillation. Water increases the rate and enantioselectivity of the reaction.
Nucleo-δ-peptides Derived from Conformationally Constrained Nucleo-δ-amino Acids: Preparation of Monomers
Karig, Gunter,Fuchs, Andreas,Buesing, Arne,Brandstetter, Tilmann,Scherer, Stefan,Rats, Jan W.,Eschenmoser, Albert,Quinkert, Gerhard
, p. 1049 - 1078 (2007/10/03)
Cyclic nucleo-δ-amino-acids that constitute monomers of a conformationally constrained nucleo-δ-peptide base-pairing system have been prepared. Their synthesis starts with an enantioselectively analyzed chirogenic Diels-Alder reaction, proceeds via a regioselective ε-iodolactamisation process, and ends with a regio- as well as stereoselective introduction of nucleobases through SN2-type opening of a transiently formed N-acylaziridine ring. Extensive use of X-ray crystal-structure analysis has been made to support structure assignments.
Synthesis of a C22-34 subunit of the immunosuppressant FK-506
Marshall,Xie
, p. 7230 - 7237 (2007/10/03)
A new route to the C22-34 subunit of FK-506 was developed. A highly diastereoselective Diels-Alder reaction of 1,3-butadiene with the bis-acrylate of (R,R)-hydrobenzoin and subsequent saponification provided the cyclohexenecarboxylic acid 6.4 of 95% ee. Elaboration to the enal 9.2 was effected by known transformations. Enal 9.2 underwent diastereoselective and enantiospecific S(E)2' addition of allenyl stannane (S)-3.9 affording the homopropargylic alcohol 9.3 as an 85:15 syn/anti mixture. The PMB ether 9.5 was converted to the known benzylidene derivative 10.4 by sequential treatment with Red-Al, epoxidation, a second reduction with Red-Al, and oxidative benzylidene formation with DDQ.
DIELS-ALDER REACTIONS OF ISOPRENE AND 1,3-BUTADIENE WITH NITROHEPTENES DERIVED FROM SUGARS
Roman, Emilio,Banos, Manuel,Gutierrez, Juan I.,Serrano, Jose A.
, p. 703 - 722 (2007/10/02)
The Diels-Alder cycloadditions of 1,3-butadiene and isoprene with D-galacto- and D-manno-(E)-nitroalkenes are described.These reactions showed an unlike stereoselectivity, as a consequence of the configuration of the adjacent chiral centre to the dienophilic double bond.For isoprene adducts, the favored regioisomers were those in which the nitro and the methyl groups on cyclohexene rings are in a 1,4-relationship.Assignment of absolute configurations at the new chiral centres in the adducts were based on NMR data and polarimetric correlations with known compounds.
221. Asymmetric Diels-Alder Reactions of Neopentyl-Ether-Shielded Acrylates and Allenic Esters: Syntheses of (-)-Norbornenone and (-)-β-Santalene
Oppolzer, Wolfgang,Chapuis, Christian,Dupuis, Dominique,Guo, Maodao
, p. 2100 - 2114 (2007/10/02)
Starting from (+)- or (-)-camphor, the antipodal alcohols 14 and 18, respectively, have been prepared; the corresponding acrylates 15 and 19 underwent TiCl2(i-PrO)2-mediated Diels-Alder additions to cyclopentadiene to give adducts 20a and 22a respectively, with 95percent endo- and 99.2percent ?-face selectivities.Adduct 22a was converted to enentiomerically pure norbornenone 26.Addition of 1,3-butadiene to acrylate 15 in the presence of TiCl4 afforded 3-cyclohexenyl carboxylate 29 with > 95.6percent stereodifferentiation.The TiCl2(i-PrO)2-promoted cycloaddition of cyclopentadiene to allenic ester 43 proceeding with 99percent face differentiation served as the key step for an efficient enantioselective synthesis of (-)-β-santalene ((-)-41) with concomitant recovery of the chiral control alcohol 14.
Camphor-Derived N-Acryloyl and N-Crotonoyl Sultams: Practical Activated Dienophiles in Asymmetric Diels-Alder Reactions
Oppolzer, Wolfgang,Chapuis, Christian,Bernardinelli, Gerald
, p. 1397 - 1401 (2007/10/02)
Starting from (+)-camphor-10-sulfonyl chloride (5), the crystalline sultam 8 was easily prepared.Lewis-acid-promoted Diels-Alder additions of the crystalline N-acryloyl and N-crotonoyl derivatives 9 and 10, respectively, to cyclopentadiene and 1,3-butadiene at -130 to -78 grad furnished adducts 11, 12 and 17 with high chiral efficiency.Crystallization of the adducts and nondestructive removal of 8 gave either alcohols 13, 14 and 18 or acid 19 in 99percent enantiomeric purity.The sense of induction was reversed on using the enantiomer of 8 as the auxiliary.The structure of 10 was established by X-ray diffraction analysis
Practical Asymmetric Diels-Alder Additions to Camphor-10-sulfonic-Acid-Derived Acrylates
Oppolzer, Wolfgang,Chapuis, Christian,Kelly, Martha J.
, p. 2358 - 2361 (2007/10/02)
Starting from (+)-camphor-10-sulfonic acid (1) the chiral crystalline alcohols 3 and 11 were prepared in two steps.Lewis-acid-mediated -additions of their acrylates to 1,3-dienes were studied.Notably, the crystalline acrylate 4 underwent TiCl2(OiPr)2-promoted Diels-Alder addition to cyclopentaniene giving after recrystallization efficiently the pure (2R)-adduct 5.
