@article { ISI:000311324100047, title = {Pd-Catalyzed imine cyclization: synthesis of antimalarial natural products aplidiopsamine A, marinoquinoline A, and their potential hybrid NCLite-M1}, journal = {Organic Letters}, volume = {14}, number = {22}, year = {2012}, month = {NOV}, pages = {5804-5807}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Palladium-catalyzed cyclization of imines has been developed to construct the extremely rare 3H-pyrrolo[2,3-c]quinoline ring system for diversity oriented first total synthesis of antimalarial marine natural product Aplidiopsamine A as well as synthesis of Marinoquinoline A and potential natural product hybrid NCLite-M1.

}, issn = {1523-7060}, doi = {10.1021/ol302676v}, author = {Mahajan, Jyoti P. and Suryawanshi, Yogeshwar R. and Mhaske, Santosh B.} } @article { ISI:000346161500008, title = {Protecting-group-free diastereoselective total synthesis of (+/-)-6-epi-cleistenolide and chemoenzymatic synthesis of (-)-6-epi-cleistenolide}, journal = {European Journal of Organic Chemistry}, number = {36}, year = {2014}, month = {DEC}, pages = {8049-8054}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

A short, efficient, practical, and protecting-group-free diastereoselective total synthesis of (+/-)-6-epi-cleistenolide (1) has been achieved in five steps in 60\% overall yield. The use of a chemoenzymatic approach also gave (-)-6-epi-cleistenolide (1) (\>99.9\% ee). The Achmatowicz reaction, chemoselective oxidation of a hemiacetal, diastereoselective 1,3-anti reduction of alpha-hydroxy ketone, and enzymatic resolution of a 1,3-diol are the key features of this linear total synthesis. The synthetic strategy demonstrated in this paper could be extended for an asymmetric total synthesis of (-)-cleistenolide (1) and related biologically active natural products.

}, keywords = {Asymmetric synthesis, diastereoselectivity, Enzyme catalysis, Lipases, Oxygen heterocycles, Total synthesis}, issn = {1434-193X}, doi = {10.1002/ejoc.201403123}, author = {Mahajan, Pankaj S. and Gonnade, Rajesh G. and Mhaske, Santosh B.} } @article { ISI:000381236300089, title = {Pd(II)-catalyzed intramolecular tandem olefin amidation/C-H activation protocol for the syntheses of the protoberberine class of natural products}, journal = {Organic Letters}, volume = {18}, number = {15}, year = {2016}, month = {AUG}, pages = {3862-3865}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A Pd(II)-catalyzed intramolecular tandem olefin amidation/C-H activation protocol has been developed for the synthesis of an 8-oxoprotoberberine core. It was successfully applied for the syntheses of (+/-)-8-oxocanadine, (+/-)-8-oxotetrahydropalmitine, and (+/-)-8-oxostylopine, which can be easily converted to the respective protoberberine natural products. The short synthetic route demonstrated would be useful for the synthesis of a large number of natural products and their analogues featuring a protoberberine scaffold.

}, issn = {1523-7060}, doi = {10.1021/acs.orglett.6b01868}, author = {Garad, Dnyaneshwar N. and Mhaske, Santosh B.} } @article {43879, title = {Pd-catalyzed regioselective mono-arylation: quinazolinone as the inherent directing group for C(sp(2))-H activation}, journal = {Journal of Organic Chemistry}, volume = {82}, year = {2017}, month = {JUN}, pages = {6366-6372}, type = {Article}, chapter = {6366-6372}, abstract = {

The Pd-catalyzed quinazolinone-directed regioselective monoarylation of aromatic rings by C-H bond activation is developed. A broad substrate scope is demonstrated for both quinazolinone as well as diary-liodonium triflates. The use of a base was found to be crucial for this transformation, unlike for the known nitrogen-directed arylations. All of the novel quinazolinones of biological interest were synthesized by using the operationally simple Pd(II)-catalyzed arylation reaction.

}, keywords = {Aromatic rings, catalysis, Chemical activation, Chemical reactions, Palladium compounds, Regioselectivity}, issn = {0022-3263}, doi = {10.1021/acs.joc.7b00948}, author = {Garad, Dnyaneshwar N. and Viveki, Amol B. and Mhaske, Santosh B.} } @article {46966, title = {Para-selective copper-catalyzed C(sp(2))-H amidation/dimerization of anilides via a radical pathway}, journal = {Chemical Communications}, volume = {56}, year = {2020}, month = {FEB }, pages = {1565-1568}, type = {Article}, abstract = {

Copper-catalyzed amidation/dimerization of anilides via regioselective C(sp(2))-H functionalization is achieved. The para-selective amidation is accomplished on the anilide aromatic ring via a radical pathway leading to C-N bond formation in the presence of ammonium persulfate as a radical source/oxidant for the copper catalyst. The developed protocol tolerates a wide range of anilide substrates. The regioselectivity is confirmed by single-crystal X-ray studies.

}, issn = {1359-7345}, doi = {10.1039/c9cc09824k}, author = {Viveki, Amol B. and Garad, Dnyaneshwar N. and Gonnade, Rajesh G. and Mhaske, Santosh B.} } @article {47704, title = {Phosphine-free manganese(II)-catalyst enables acceptorless dehydrogenative coupling of alcohols with indoles}, journal = {Advanced Synthesis \& Catalysis}, volume = {363}, year = {2021}, month = {SEP }, pages = {4430-4439}, type = {Article}, abstract = {Herein, an air-stable, molecularly defined NNN-Mn(II) pincer complex catalyzed acceptorless dehydrogenative coupling of alcohols with indoles is reported. A wide variety of symmetrical and unsymmetrical bis(indolyl)methane derivatives as well as some structurally important products such as Vibrindole A, Turbomycin B alkaloid, Antileukemic, and Anticancer agents were synthesized. Mechanistic studies illustrate the importance of the NH moiety in the complex and the crucial role of metal-ligand cooperation during catalysis.}, keywords = {acceptorless dehydrogenation, Alcohol, Indole, manganese, phosphine-free}, issn = {1615-4150}, doi = {10.1002/adsc.202100621}, author = {Yadav, Vinita and Balaraman, Ekambaram and Mhaske, Santosh B.} } @article {47061, title = {Photoactivatable prodrug for simultaneous release of mertansine and CO along with a BODIPY derivative as a luminescent marker in mitochondria: a proof of concept for NIR image-guided cancer therapy}, journal = {Chemical Science}, volume = {12}, year = {2021}, month = {FEB}, pages = {2667-2673}, type = {Article}, abstract = {

Controlled and efficient activation is the crucial aspect of designing an effective prodrug. Herein we demonstrate a proof of concept for a light activatable prodrug with desired organelle specificity. Mertansine, a benzoansamacrolide, is an efficient microtubule-targeting compound that binds at or near the vinblastine-binding site in the mitochondrial region to induce mitotic arrest and cell death through apoptosis. Despite its efficacy even in the nanomolar level, this has failed in stage 2 of human clinical trials owing to the lack of drug specificity and the deleterious systemic toxicity. To get around this problem, a recent trend is to develop an antibody-conjugatable maytansinoid with improved tumor/organelle-specificity and lesser systematic toxicity. Endogenous CO is recognized as a regulator of cellular function and for its obligatory role in cell apoptosis. CO blocks the proliferation of cancer cells and effector T cells, and the primary target is reported to be the mitochondria. We report herein a new mitochondria-specific prodrug conjugate (Pro-DC) that undergoes a photocleavage reaction on irradiation with a 400 nm source (1.0 mW cm(-2)) to induce a simultaneous release of the therapeutic components mertansine and CO along with a BODIPY derivative (BODIPY(PPH3)(2)) as a luminescent marker in the mitochondrial matrix. The efficacy of the process is demonstrated using MCF-7 cells and could effectively be visualized by probing the intracellular luminescence of BODIPY(PPH3)(2). This provides a proof-of-concept for designing a prodrug for image-guided combination therapy for mainstream treatment of cancer.

}, issn = {2041-6520}, doi = {10.1039/d0sc06270g}, author = {Tiwari, Rajeshwari and Shinde, Prashant S. and Sreedharan, Sreejesh and Dey, Anik Kumar and Vallis, Katherine A. and Mhaske, Santosh B. and Pramanik, Sumit kumar and Das, Amitava} } @article {48700, title = {PIDA-mediated N-N bond formation to access pyrazolidine-3,5-diones: a novel process for uricosuric agents G-25671 and sulfinpyrazone}, journal = {Chemical Communications}, volume = {59}, year = {2023}, month = {JUN }, pages = {8242-8245}, type = {Article}, abstract = {

Traditionally, toxic and expensive hydrazine building blocks are required to construct pharmaceutically important pyrazolidine-3,5-diones. Herein, we have described a novel method for their synthesis based on metal-free oxidative dehydrogenative N-N bond formation by PIDA-mediated reaction of easily accessible dianilide precursors. The developed mild reaction protocol features a good functional group tolerance and scalability. The application of this method is demonstrated by offering a unique route for the synthesis of uricosuric agents G-25671 and sulfinpyrazone from inexpensive starting material aniline via smooth functionalization of the well-designed diversity-oriented cyclopropyl key intermediate.

}, issn = {1359-7345}, doi = {10.1039/d3cc02078a}, author = {Halder, Priyanka and Mhaske, Santosh B.} }