5681-56-1Relevant 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%).
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.
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.
Asymmetric Diels-Alder Reaction: Applications of Chiral Dienophiles
Masamune, Satoru,Reed, Lawrence A.,Davis, Jeffery T.,Choy, William
, p. 4441 - 4444 (2007/10/02)
The chiral dienophile recently designed and its related compounds react highly diastereoselectively with a wide variety of both achiral and chiral dienes, and the stereochemical outcome of these Diels-Alder reactions is predictable.
Efficient Enantioselective Synthesis of the Antitumor Agent Sarkomycin
Boeckman, Robert K.,Naegely, Paul C.,Arthur, Samuel D.
, p. 752 - 754 (2007/10/02)
An efficient total synthesis of (+/-)-sarkomycin (1) is described via bicyclic lactone 8.Preparation of a key precursor (R)-(+)-6 via an asymmetric Diels-Alder reaction affords the correct enantiomer for the preparation of natural (R)-(-)-sarkomycin (1) in high optical yield.
