Coreychem is committed to continuously explore new compound synthesis technology in recent years, we were on enzyme catalysis, catalytic metal complexes in the total synthesis was tested and achieved good results. Were synthesized S. lycopersicum (+) - Aszonalenin (+) - Citrinadin B. Briefly explain the specific methods.
Biosynthesis of Lycosantalonol
Biosynthesis of Lycosantalonol 4 from 1 via 2 and 3 Catalyzed by S1CPT2 S1TPS21 and CYP71D51.
.Compound is first cyclized to a tricyclene core ring structure analogous to that found in α-santalene, with the resulting diterpene termed here lycosantalene (2). Quantum chemical calculations indicate a role for the diphosphate anion coproduct in this cyclization reaction. Subsequently, the internal cis double bond of the neryl side chain in 2 is then further transformed to an α-hydroxy ketone moiety via an epoxide intermediate (3). Oxygen labeling studies indicate 3 undergoes oxidative conversion to lycosantalonol (4)
Compounds 4 were isolated in amounts (1.5 mg) sufficient for comprehensive NMR analysis, while 4 contains a C13,12 α-hydroxy ketone (Figures S25 −S30 and Table S4, SI) and also exhibits positive optical rotation; [α] 23D, +13.8 (c 0.2, CHCl3) .
Total Synthesis of ( − )-Brevicompanine B by Ir-Catalyzed
Metal-catalyzed reverse prenylation of oxindoles and C3 unsubstituted indoles has been reported under a variety of conditions. However, to the best of our knowledge, general methods for the one-step reverse prenylation of 3-substituted indoles at C3 have not been described previously.4 Of additional importance, iridiumcatalyzed allylations to access products with vicinal quaternary centers is unprecedented. Brevicompanine is a plant growth regulator isolated from Penicillium brevicompactum.
The use of tryptophan (free) amino ester 1 as substrate in a reaction gave product 5 in 50% yield Hexahydropyrrolo[2,3-b]indole ( −)-exo-5 has been previously employed for the syntheses of various ardeemins and amauromine alkoids ( −)-brevicompanine B was readily obtained by coupling ( −)-exo-5 to (R)-Fmoc-Leu, followed by deprotection and cyclization. The synthesis of ( − )-Brevicompanine B
we have described is effected in three steps from commercially available (S)-tryptophan methyl ester (39% overall yield), which compares favorably to the only synthesis reported so far (9 steps, 11% overall yield) [α] D22= –258.0° (c0.67, CHCl3).
Total Synthesis of (+)-Citrinadin B
(+)-citrinadin B exhibit notable activity against murine leukemia L1210 (1, IC50 6.2 μg/mL; 2, 10 μg/mL) and human epidermoid carcinoma KB cells (1, IC50 10 μg/mL). The concise, enantioselective total syntheses of (+)-citrinadin B in a total of only 21 steps, respectively, from commercially available starting materials are described. Our strategy, which minimizes refunctionalization and protection/deprotection operations, features the highly diastereoselective, addition of a dienolate to a chiral pyridinium salt to set the first chiral center. The absolute stereochemistry of this key center was then relayed by a sequence of substrate-controlled reactions, including a highly stereoselective epoxidation/ring opening sequence and an oxidative rearrangement of an indole to furnish a spirooxindole to establish the remaining stereocenters in the pentacyclic core of the citrinadins.
Barton deoxygenation of 1 afforded 2 in 73% yield (Scheme14). Epoxidation of 2 using buffered peroxytrifluoroacetic acid gave epoxide 3 (77% yield) as a single stereoisomer, and when 3 was heated with aqueous methylamine, the desired amino alcohol 4 was isolated in 94% yield. The Fisher indole reaction of 4 with o-bromophenylhydrazine hydrochloride furnished the pentacyclic indole 5, which was then converted into the spirooxindole 6 in 34% overall yield by sequential hydride reduction of the tertiary lactam, indole oxidation with Davis’ oxaziridine, and acid-catalyzed rearrangement of the intermediate epoxide. The aryl bromide moiety of 6 was then elaborated via a Sonogashira coupling with 3-methylbut-1- yne to furnish the alkyne 7 that was processed to the enone8 in 68% overall yield from 6 by reaction with 2-bromopyridine N-oxide in the presence of gold.Finally, epoxidation of enone 8 using the Enders procedure afforded a separable mixture of 9 and 10
The CD spectrum of major isomer 7was in agreement with CD data obtained for natural (+)-citrinadin (B), and the spectral data (1H and 13C NMR) of the synthetic 7 thus isolated were consistent with those reported by Wood （1）.