166239-59-4Relevant academic research and scientific papers
A Catalyst Designed for the Enantioselective Construction of Methyl- and Alkyl-Substituted Tertiary Stereocenters
Claraz, Aurlie,Sahoo, Gokarneswar,Berta, Dnes,Madarsz, dm,Ppai, Imre,Pihko, Petri M.
, p. 669 - 673 (2016/02/27)
Tertiary methyl-substituted stereocenters are present in numerous biologically active natural products. Reported herein is a catalytic enantioselective method for accessing these chiral building blocks using the Mukaiyama-Michael reaction between silyl ketene thioacetals and acrolein. To enable remote enantioface control on the nucleophile, a new iminium catalyst, optimized by three-parameter tuning and by identifying substituent effects on enantioselectivity, was designed. The catalytic process allows rapid access to chiral thioesters, amides, aldehydes, and ketones bearing an α-methyl stereocenter with excellent enantioselectivities, and allowed rapid access to the C4-C13 segment of (-)-bistramide A. DFT calculations rationalized the observed sense and level of enantioselectivity.
Application of in situ-generated Rh-bound trimethylenemethane variants to the synthesis of 3,4-fused pyrroles
Schultz, Erica E.,Sarpong, Richmond
supporting information, p. 4696 - 4699 (2013/05/09)
Rh-bound trimethylenemethane variants generated from the interaction of a Rh-carbenoid with an allene have been applied to the synthesis of substituted 3,4-fused pyrroles. The pyrrole products are useful starting points for the syntheses of various dipyrromethene ligands. Furthermore, the methodology has been applied to a synthesis of the natural product cycloprodigiosin, which demonstrates antitumor and immunosuppressor activity.
Total Synthesis of Tautomycin
Oikawa, Masato,Ueno, Tohru,Oikawa, Hideaki,Ichihara, Akitami
, p. 5048 - 5068 (2007/10/02)
A convergent stereocontrolled synthesis of the antifungal antibiotic tautomycin, a potent protein phosphatases inhibitor, has been achieved first via key aldol coupling of two large subunits, a right-hand C1-C21 ketone and a left-hand aldehyde (left from C22).The C1-C10 segment was synthesized through a remote stereochemical control process using a spiroketal template.After joining with the C11-C18 segment, the spiroketal moiety was selectively constructed.Then the right-hand C1-C21 ketone was synthesized via Roush asymmetric crotylboration.The left-hand aldehyde was prepared from a C21-C26 segment and a dialkylmaleic anhydride segment.Completely stereoselective assemblage of the two subunits, the right-hand and the left-hand, was achieved by employing the Mukaiyama aldol reaction.Further functional group manipulation including desilylation, oxidation at C2, and deprotection of tert-butyl ester with concomitant anhydride formation provided tautomycin which was identical with the natural product.As a preliminary study, derivatizations and degradation of the natural product were also examined to support the total synthesis.
Synthetic study on tautomycin. Stereocontrolled synthesis of C(1)-C(18) fragment using a strategy of selective reduction of spiroketal
Oikawa,Oikawa,Ichihara
, p. 4797 - 4800 (2007/10/02)
A stereocontrolled synthesis of C(1)-C(18) fragment of tautomycin is accomplished employing asymmetric crotylboration, selective reduction of spiroketal, and addition of crotylstannane as the key steps.
