A well-ordered strategy of sulfoxonium ylides as a directing group as well as carbene source for the Ru-catalysed [4+2] and Rh-catalysed [4+1] carbo-annulations with maleimides has been described. These novel methodologies have been successfully established for the synthesis of complex spiroindanones and benzoisoindoles containing compounds by the transition metal-mediated C-H activation/functionalization reactions. Further, Rh-catalysed [4+1] annulated compounds were obtained in the absence of any oxidant. A possible rationale for the remarkable divergent selectivity between the two catalysts has been proposed.

We herein demonstrate the acylsilane-directed Rh-catalyzed arene C-H bond alkylation with maleimides. The resulting derivatives were utilized in visible-light-induced intramolecular siloxycarbene-amide cyclization for the synthesis of new tricyclic γ-lactams. In parallel, we also harnessed the same acylsilane and maleimide units through [3 + 2] carbo-annulation by using Ru-catalysis. A wide range of maleimides and aroylsilanes were used to establish the broadness of these transformations.

The synthesis of various bridged azacyclic adducts has recently become a reemerging topic due to their bioactive and natural product mimic profiles. Accordingly, herein, we report a method for easy access to succinamide-bridged azacyclic derivatives through the metal-free polarization-controlled dual C-N/C-C annulation of readily available α-amino acids, 2-amino benzaldehydes or pyrrole/indole-2-aldehyde and maleimide substrates. This cascade features a rare dipolarophile-induced diastereo-selective amidative annulation, followed by 3 + 2 cycloaddition as key steps.

A formal diastereoselective 1,3-dipolar cycloaddition of azomethine ylide and coumarin derivatives to construct coumarin based spiro multi heterocyclics has been described. The in situ generation of azo-ylide was achieved for various heterocyclic carbonyls (indenoquinoxaline and isatin). This transformation is also suitable for maleimide dipolarophiles for the synthesis of hydro-maleimide derivatives. These decarboxylative annulations neither required any catalyst nor any activator. Further the pure products were isolated by filtration from the reaction mixture after the reaction under ambient conditions.

α‐β‐unsaturated acylsilanes are excellent substrates for Morita–Baylis–Hillman (MBH) reactions, affording the expected adducts in good to excellent yields. In these derivatives, as well as the corresponding acetates, the acylsilanes can be smoothly transformed into aldehydes by irradiation at 365 nm in acetone or THF/water mixtures. Therefore α‐β unsaturated acylsilanes are very useful surrogates for acrolein in MBH reactions, allowing easy preparation of simple and highly functionalized new building blocks for synthetic applications.

The first total synthesis of recently isolated 5(S)-hydroxyrecifeiolide has been described in ten straight forward linear steps with 14% of overall yield. The key reaction involves Jacobsen’s hydrolytic kinetic resolution, Copper catalysed Grignard reaction, Steglich esterification and ring closing metathesis reaction using Grubb's 2nd generation catalyst making the synthesis very elegant and simple. The stereogenic center at C5 was generated via Jacobsen's HKR which was confirmed by the Mandelate ester strategy as well as HPLC purity.

A first stereoselective total synthesis of 14-memebered beta-resorcylic macrolactone 5 '-hydroxyzearalenone (1) has been achieved. The key steps are Jocobsen hydrolytic kinetic resolution, Sharpless asymmetric dihydroxylation, Vilsmeier-Haack reaction, Mitsunobu esterification and ring-closing metathesis. (C) 2018 Published by Elsevier Ltd.

A formal, stereoselective synthesis of Aspergillide-B is described. A highly diastereoselective Pd(0)-B(OPh)(3) mediated syn-vic-diol formation from epoxy unsaturated ester used for the creation of C3-C4 centres. Iodine catalyzed allylation used for synthesis of trans-2,6-disubstitutedtetrahydro-2H-Pyran. Cross- metathesis, Yamaguchi macrolactonization are the other key features of the synthesis.

Stereoselective total syntheses of pinguisane type of sesquiterpenoids are described following a unified approach using a chiral building block derived from (R)-pulegone. The functionality embodied in the key intermediate enables their facile elaboration into more complex structures of biological relevance such as acutifolone A (9 steps, 22% overall yield) and bisacutifolone A and B (6 and 8%, respectively) following Furukawa's modified Simmons-Smith cyclopropanation, Luche reduction, Saegusa-Ito oxidation, pyridinium chlorochromate-mediated 1,3-oxidative transposition, and Diels-Alder dimerization as key steps.

Fellutamide B is reported to have cytotoxic and proteasome inhibitory activity. Interestingly, fellutamide B and its simplified analogues have also been observed for the neurotrophic activity by stimulating the synthesis and secretion of neurotrophins. Owing to the interesting structural and potent neurotrophic role of fellutamide B (a lipopeptide aldehyde), we have assessed the synthetic path intermediates (compounds A-D) of fellutamide B for their neuroactive potential (in vitro and in vivo). We have observed few compounds (comp #A-D) to have potential neurite outgrowth activity in Neuro2a cells with no observable negative effect on the cell viability. In addition, most compounds (comp #A, C, and D) have shown neurogenic activity ex vivo in hippocampal neurosphere culture, with increased acetyl H3 and acetyl H4 induction ability (comp #C). Furthermore, the intermediate product comp #C has shown anxiolytic and antidepressant-like activity in novel tank test and social interaction test, in the chronic unpredictable stress model of zebrafish mood disorder, inducing BDNF gene expression in the telencephalon region of the fish brain. Our results thus demonstrate that the fellutamide B synthetic path intermediates have potential neurotrophic, neurogenic, and mood-elevating effects and thus good prospect to be developed as potential therapeutics to treat psychiatric disorders.

A short and efficient enantioselective approach to pinguisane-type sesquiterpenes has been developed starting from a Hajos-Parrish-type ketone. This led to the first total syntheses of isonaviculol (10 steps, 6.6 % overall yield) and natural pinguisenol (9 steps, 12 % overall yield). The key reactions were regioselective thioketal protection, stereoselective cyclopropanation using Furukawa's protocol, diastereoselective hydrogenation of an olefin using a Thalesnano H-Cube Pro flow reactor, Li/liquid NH3 mediated cyclopropane reduction, and a PCC-mediated 1,3-oxidative transposition sequence.

An efficient stereoselective total synthesis of 12-membered macrolide dendrodolide L has been achieved. The key reactions involved are Keck asymmetric allylation, Jacobsen’s hydrolytic kinetic resolution, Sharpless asymmetric epoxidation, Mitsunobu reaction and ring-closing metathesis reaction.

The first stereoselective synthesis of polyketide natural product (3R,6S)-6-hydroxylasiodiplodin (1) has been described starting from commonly available starting materials D-mannitol and 2,4,6-trihydroxybenzoic acid. The key reactions involved are Keck asymmetric allylation, Stille coupling, De Brabander's esterification, and ring-closing metathesis (RCM) reaction. The total synthesis was achieved in 19.3% overall yield making the route significant. (C) 2016 Elsevier Ltd. All rights reserved.

A facile and stereoselective synthesis of C1–C9 and C9–C17 fragments of (+)-13-deoxytedanolide and studies towards the synthesis of (+)-13-deoxytedanolide was accomplished in 20 linear steps. The key transformations of fragment 6 are Sharpless asymmetric dihydroxylation and preparation of terminal olefin from primary alcohol utilising organo selenium reaction. The key transformations of fragment 7 are from Sharpless epoxidation and Crimmin’s syn aldol chemistry.

The stereoselective total synthesis of resorcylic acid lactone, paecilomycin G (1) has been accomplished. The key steps involved are the Corey Fuchs reaction, Sharpless asymmetric dihydroxylation, Jacobsen hydrolytic kinetic resolution, Stille coupling, Mitsunobu reaction, and Ring-closing metathesis (RCM) reaction. (C) 2016 Elsevier Ltd. All rights reserved.

The first total syntheses of diarylheptanoid natural products (2R,4S,6R)-2-(4-hydroxyphenethyl)-6-(4-hydroxyphenyl) tetrahydro-2H-pyran-4-ol (4) and (3R,5R)-1,7-bis (4-hydroxyphenyl)heptane-3,5-diol (12) were accomplished using substrate selective hydrogenation, ring cleavage of tetrahydropyran ring, and Keck–Maruoka allylation as the key synthetic steps.

ChemInformVolume 46, Issue 11 Natural Products ChemInform Abstract: Formal Synthesis of (.+-.)-Brazilin (I) and Total Synthesis of (.+-.)-Brazilane (II). Jhillu Singh Yadav, Jhillu Singh Yadav Nat. Prod. Chem. Div., Indian Inst. Chem. Technol., Hyderabad 500 007, IndiaSearch for more papers by this authorAnand Kumar Mishra, Anand Kumar Mishra Nat. Prod. Chem. Div., Indian Inst. Chem. Technol., Hyderabad 500 007, IndiaSearch for more papers by this authorSaibal Das, Saibal Das Nat. Prod. Chem. Div., Indian Inst. Chem. Technol., Hyderabad 500 007, IndiaSearch for more papers by this author Jhillu Singh Yadav, Jhillu Singh Yadav Nat. Prod. Chem. Div., Indian Inst. Chem. Technol., Hyderabad 500 007, IndiaSearch for more papers by this authorAnand Kumar Mishra, Anand Kumar Mishra Nat. Prod. Chem. Div., Indian Inst. Chem. Technol., Hyderabad 500 007, IndiaSearch for more papers by this authorSaibal Das, Saibal Das Nat. Prod. Chem. Div., Indian Inst. Chem. Technol., Hyderabad 500 007, IndiaSearch for more papers by this author First published: 24 February 2015 https://doi.org/10.1002/chin.201511281Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume46, Issue11March, 2015 RelatedInformation

AbstractSynthetically important β‐hydroxyacylsilanes are available with good to excellent diastereoselectivity under mild conditions.

A convenient solution phase approach for the synthesis of fellutamide B with efficient purification techniques has been demonstrated on the molecule for the first time. The strategy involves the use of natural amino acids as starting materials and classical peptide coupling reactions. The synthesis has been achieved in 10 steps with overall yield of 26.7% making the synthesis facile.

A facile and stereoselective synthesis of vittarilide-A, having promising antioxidant property was accomplished in 12 linear synthetic steps with an overall yield of 6.34% using a chiral pool approach from naturally available diethyl tartrate. The key reactions employed were diastereoselective vinylation, Sharpless asymmetric dihydroxylation, (2,2,6,6-tetramethylpiperidin-1-yl)oxy radical (TEMPO), bis(acetoxy)iodo-benzene (BAIB) mediated tandem oxidation followed by lactonization and finally esterification under Yamaguchi conditions.