1693-83-0Relevant articles and documents
Chiral Br?nsted-Acid-Catalyzed Asymmetric Oxidation of Sulfenamide by Using H2O2: A Versatile Access to Sulfinamide and Sulfoxide with High Enantioselectivity
Ma, Long-Jun,Chen, Shu-Sen,Li, Guang-Xun,Zhu, Jin,Wang, Qi-Wei,Tang, Zhuo
, p. 1525 - 1530 (2019)
Herein, we describe an example of catalytic asymmetric synthesis of sulfinamides. Aromatic sulfenamides were chosen as useful substrates, because of the indispensable N-H bond, which could form an efficient hydrogen bond with chiral phosphoric acid. Hsub
Investigation of functionalized α-chloroalkyllithiums for a stereospecific reagent-controlled homologation approach to the analgesic alkaloid (-)-epibatidine
Emerson, Christopher R.,Zakharov, Lev N.,Blakemore, Paul R.
supporting information, p. 16342 - 16356 (2013/12/04)
Four putative functionalized α-chloroakyllithiums RCH 2CHLiCl, where R=CHCH2 (18 a), CCH (18 b), CH 2OBn (18 c), and CH[O(CH2)2O] (18 d), were generated in situ by sulfoxide-lithium exchange from α-chlorosulfoxides, and investigated for the stereospecific reagent-controlled homologation (StReCH) of phenethyl and 2-chloropyrid-5-yl (17) pinacol boronic esters. Deuterium labeling experiments revealed that α-chloroalkyllithiums are quenched by proton transfer from their α-chlorosulfoxide precursors and it was established that this effect compromises the yield of StReCH reactions. Use of α-deuterated α-chlorosulfoxides was discovered to ameliorate the problem by retarding the rate of acid-base chemistry between the carbenoid and its precursor. Carbenoids 18 a and 18 b showed poor StReCH efficacy, particularly the propargyl group bearing carbenoid 18 b, the instability of which was attributed to a facile 1,2-hydride shift. By contrast, 18 d, a carbenoid that benefits from a stabilizing interaction between O and Li atoms gave good StReCH yields. Boronate 17 was chain extended by carbenoids 18 a, 18 b, and 18 d in 16, 0, and 68 % yield, respectively; α-deuterated isotopomers D-18 a and D-18 d gave yields of 33 and 79 % for the same reaction. Double StReCH of 17 was pursued to target contiguous stereodiads appropriate for the total synthesis of (-)-epibatidine (15). One-pot double StReCH of boronate 17 by two exposures to (S)-D-18 a (≤66 % ee), followed by work-up with KOOH, gave the expected stereodiad product in 16 % yield (d.r.～67:33). The comparable reaction using two exposures to (S)-D-18 d (≤90 % ee) delivered the expected bisacetal containing stereodiad (R,R)-DD-48 in 40 % yield (≥98 % ee, d.r.=85:15). Double StReCH of 17 using (S)-D-18 d (≤90 % ee) followed by (R)-D-18 d (≤90 % ee) likewise gave (R,S)-DD-48 in 49 % yield (≥97 % ee, d.r.=79:21). (R,S)-DD-48 was converted to a dideuterated isotopomer of a synthetic intermediate in Corey's synthesis of 15. Copyright
Desymmetrization of prochiral diaryl sulfoxides by an asymmetric sulfoxide-magnesium exchange
Hampel, Thomas,Ruppenthal, Simon,Saelinger, Daniel,Brueckner, Reinhard
supporting information; experimental part, p. 3136 - 3140 (2012/05/20)
The first desymmetrizations of prochiral diaryl sulfoxides 1 by an asymmetric sulfoxide-magnesium exchange reaction are reported. The respective substrate (1), iPr2Mg, and the dilithium salt of (S)-BINOL (which was prepared in situ) provided (S)-configured aryl isopropyl sulfoxides 2 in up to 91 % yield and with up to 91 % ee. (S)-BINOL was re-isolable in 98 % yield. Copyright
