138713-55-0Relevant articles and documents
Bioproduction of Enantiopure (R)- and (S)-2-Phenylglycinols from Styrenes and Renewable Feedstocks
Sekar, Balaji Sundara,Mao, Jiwei,Lukito, Benedict Ryan,Wang, Zilong,Li, Zhi
, p. 1892 - 1903 (2020/12/22)
Enantiopure (R)- and (S)-2-phenylglycinols are important chiral building blocks for pharmaceutical manufacturing. Several chemical and enzymatic methods for their synthesis were reported, either involving multi-step synthesis or starting from a relatively complex chemical. Here, we developed one-pot simple syntheses of enantiopure (R)- and (S)-2-phenylglycinols from cheap starting materials and renewable feedstocks. Enzyme cascades consisting of epoxidation-hydrolysis-oxidation-transamination were developed to convert styrene 2 a to (R)- and (S)-2-phenylglycinol 1 a, with butanediol dehydrogenase for alcohol oxidation as well as BmTA and NfTA for (R)- and (S)-enantioselective transamination, respectively. The engineered E. coli strains expressing the cascades produced 1015 mg/L (R)-1 a in >99% ee and 315 mg/L (S)-1 a in 91% ee, respectively, from styrene 2 a. The same cascade also converted substituted styrenes 2 b–k and indene 2 l into substituted (R)-phenylglycinols 1 b–k and (1R, 2R)-1-amino-2-indanol 1 l in 95–>99% ee. To transform bio-based L-phenylalanine 6 to (R)-1 a and (S)-1 a, (R)- and (S)-enantioselective enzyme cascades for deamination-decarboxylation-epoxidation-hydrolysis-oxidation-transamination were developed. The engineered E. coli strains produced (R)-1 a and (S)-1 a in high ee at 576 mg/L and 356 mg/L, respectively, from L-phenylalanine 6, as the first synthesis of these compounds from a bio-based chemical. Finally, L-phenylalanine biosynthesis pathway was combined with (R)- or (S)-enantioselective cascade in one strain or coupled strains, to achieve the first synthesis of (R)-1 a and (S)-1 a from a renewable feedstock. The coupled strain approach enhanced the production, affording 274 and 384 mg/L (R)-1 a and 274 and 301 mg/L (S)-1 a, from glucose and glycerol, respectively. The developed methods could be potentially useful to produce these high-value chemicals from cheap starting materials and renewable feedstocks in a green and sustainable manner. (Figure presented.).
Catalytic β C-H amination: Via an imidate radical relay
Stateman, Leah M.,Wappes, Ethan A.,Nakafuku, Kohki M.,Edwards, Kara M.,Nagib, David A.
, p. 2693 - 2699 (2019/03/06)
The first catalytic strategy to harness imidate radicals for C-H functionalization has been developed. This iodine-catalyzed approach enables β C-H amination of alcohols by an imidate-mediated radical relay. In contrast to our first-generation, (super)stoichiometric protocol, this catalytic method enables faster and more efficient reactivity. Furthermore, lower oxidant concentration affords broader functional group tolerance, including alkenes, alkynes, alcohols, carbonyls, and heteroarenes. Mechanistic experiments interrogating the electronic nature of the key 1,5 H-atom transfer event are included, as well as probes for chemo-, regio-, and stereo-selectivity.
Directed β C-H Amination of Alcohols via Radical Relay Chaperones
Wappes, Ethan A.,Nakafuku, Kohki M.,Nagib, David A.
, p. 10204 - 10207 (2017/08/10)
A radical-mediated strategy for β C-H amination of alcohols has been developed. This approach employs a radical relay chaperone, which serves as a traceless director that facilitates selective C-H functionalization via 1,5-hydrogen atom transfer (HAT) and enables net incorporation of ammonia at the β carbon of alcohols. The chaperones presented herein enable direct access to imidate radicals, allowing their first use for H atom abstraction. A streamlined protocol enables rapid conversion of alcohols to their β-amino analogs (via in situ conversion of alcohols to imidates, directed C-H amination, and hydrolysis to NH2). Mechanistic experiments indicate HAT is rate-limiting, whereas intramolecular amination is product- and stereo-determining.
