01358nas a2200181 4500008004100000022001400041245016700055210006900222260000900291300001400300490000700314520063400321100002600955700001900981700002401000700002201024856013001046 2019 eng d a1523-706000aFe(III)-Catalyzed diastereoselective friedel-crafts alkylation-hemiketalization-lactonization cascade for the synthesis of polycyclic bridged 2-chromanol lactones0 aFeIIICatalyzed diastereoselective friedelcrafts alkylationhemike cAPR  a2629-26330 v213 a

An unprecedented Fe(III)-catalyzed Friedel-rafts alkylation-hemiketalization-lactonization cascade of electron-rich hydroxy arenes and distinctively functionalized unsaturated 4-keto esters is developed for the construction of polycyclic bridged 2-chromanol lactones. Following this simple and facile protocol, a broad range of products was prepared in good to excellent yields as a single diastereomer. An unusual conglomerate (enantiomerically pure polymorph) of 3ac is reported along with the absolute stereochemistry, and the remaining products were rigorously confirmed by single-crystal X-ray analysis and analogy.

1 aBorade, Balasaheb, R.1 aNomula, Rajesh1 aGonnade, Rajesh, G.1 aKontham, Ravindar uhttp://library.ncl.res.in/content/feiii-catalyzed-diastereoselective-friedel-crafts-alkylation-hemiketalization-lactonization01389nas a2200169 4500008004100000022001400041245007500055210006900130260000900199300001400208490000700222520082100229100002601050700001701076700002201093856010401115 2020 eng d a1523-706000aTotal synthesis of beshanzuenone D and its epimers and abiespiroside A0 aTotal synthesis of beshanzuenone D and its epimers and abiespiro cNOV  a8561-85650 v223 a

A unified and protecting-group-free six-step total synthesis of bisabolane-type sesquiterpenoid beshanzuenone D and its stereoisomers and abiespiroside A using S-(+)-carvone as a common chiral-pool building block is disclosed. This synthetic route features chemoselective allylic chlorination of carvone, Au(I)-catalyzed cydoisomerization induced construction of furan from homopropargylic diol, substrate-controlled selective hydroxylation using Davis-oxaziridine, and dye-sensitized photo-oxidation (through O-1(2)) of hydroxyalkyl tethered furan to access oxaspirolactone as key transformations. A comprehensive set of NMR data along with DFT calculations, ECD spectra, and optical rotation measurements of the synthesized beshanzuenone D and its epimers were obtained to confirm absolute configurations.

1 aBorade, Balasaheb, R.1 aDixit, Ruchi1 aKontham, Ravindar uhttp://library.ncl.res.in/content/total-synthesis-beshanzuenone-d-and-its-epimers-and-abiespiroside01175nas a2200169 4500008004100000022001400041245014500055210006900200260000900269300001400278490000700292520050300299100002600802700002600828700002200854856012900876 2021 eng d a1477-052000aBismuth(iii)-catalyzed bis-cyclization of propargylic diol-esters: a unified approach for the synthesis of [5,5]- and [6,5]-oxaspirolactones0 aBismuthiiicatalyzed biscyclization of propargylic diolesters a u cAUG  a6618-66220 v193 aHerein we disclose an unprecedented intramolecular cascade strategy for the construction of alpha,beta-unsaturated [5,5]- and [6,5]-oxaspirolactones that capitalizes on the pi-electrophilic Lewis acid-catalyzed 5-exo-dig or 6-exo-dig mode of cyclization of propargylic diol esters, followed by dehydration and spirolactonization steps. Moreover, semi-protected substrates also delivered the respective oxaspirolactones with the same ease and in appreciable yields under optimal reaction conditions.1 aKambale, Digambar, A.1 aBorade, Balasaheb, R.1 aKontham, Ravindar uhttp://library.ncl.res.in/content/bismuthiii-catalyzed-bis-cyclization-propargylic-diol-esters-unified-approach-synthesis-5501531nas a2200157 4500008004100000022001400041245008900055210006900144260000800213300001600221490000700237520097100244100002601215700002201241856011001263 2022 eng d a0022-326300aConcise total synthesis of (+)-lanceolactone a: revision of absolute stereochemistry0 aConcise total synthesis of lanceolactone a revision of absolute  cOCT a12867-128760 v873 a

A chiral-pool protecting-group-free five-step total synthesis of tetranorsesquiterpenoide (+)-lanceolactone A and all of its four stereoisomers using (S)-(+)-, and (R)-(-)-linalool (coriandrol) as building blocks is disclosed. The key steps involved in this synthetic route are regioselective ozonolysis, Au(I)-catalyzed cycloisomerization-induced construction of furan from alleneone, and dye-sensitized photo-oxidation (through O-1(2) ; singlet oxygen) of hydroxyalkyl-tethered furan to access oxaspirolactone. After a thorough evaluation of electronic circular dichroism (ECD) and optical rotation data of all possible stereoisomers, the absolute configuration of natural lanceolactone A at the C4 and C7 positions has been assigned as (+)-(4S,7S), which is an enantiomer to the initially proposed structure (+)-(4R,7R). Further, these investigations led us to extend Feringa and Gawronski's CD correlation method to [5,5]- and [6,5]-oxaspirolactones.

1 aBorade, Balasaheb, R.1 aKontham, Ravindar uhttp://library.ncl.res.in/content/concise-total-synthesis-lanceolactone-revision-absolute-stereochemistry01351nas a2200217 4500008004100000022001400041245013700055210006900192260000800261300001400269490000700283520056800290100002000858700002300878700002600901700002000927700002100947700002200968700002300990856012001013 2022 eng d a0163-386400aEnceleamycins A-C, furo-naphthoquinones from amycolatopsis sp. MCC0218: isolation, structure elucidation, and antimicrobial activity0 aEnceleamycins AC furonaphthoquinones from amycolatopsis sp MCC02 cMAY a1267-12730 v853 a

Three novel furo-naphthoquinones, enceleamycins A-C (1-3), and a new N-hydroxypyrazinone acid (4) were identified from the strain Amycolatopsis sp. MCC 0218, isolated from a soil sample collected from the Western Ghats of India. Their chemical structure and absolute and relative configurations were established by 1D and 2D NMR spectroscopy, single-crystal X-ray crystallography, and high-resolution mass spectrometry. Compounds 1 and 3 were active against methicillin-susceptible and -resistant Staphylococcus aureus with MIC values of 2-16 mu g/mL.

1 aKhan, Abujunaid1 aSaid, Madhukar, S.1 aBorade, Balasaheb, R.1 aGonnade, Rajesh1 aBarvkar, Vitthal1 aKontham, Ravindar1 aDastager, Syed, G. uhttp://library.ncl.res.in/content/enceleamycins-c-furo-naphthoquinones-amycolatopsis-sp-mcc0218-isolation-structure01311nas a2200181 4500008004100000022001400041245015100055210006900206260000900275300001600284490000700300520059200307100002600899700002600925700002500951700002200976856013100998 2023 eng d a0022-326300aDivergent synthesis of oxepino-phthalides and [5,5]-oxaspirolactones through [2+2+2]- and [2+3]-annulation of alkynyl alcohols with a-ynone-esters0 aDivergent synthesis of oxepinophthalides and 55oxaspirolactones  cAUG  a12597-126120 v883 a

Unmasking the synthetic potential of alkyne functional group of alkynyl alcohols as surrogates of carbonyl compounds, herein we present the first Bronsted acid (TfOH)-catalyzed [2 + 2 + 2]-annulation of 4-pentyn-1-ols (possessing terminal alkyne) with a-ynone-esters to access tricyclic tetrahydro-oxepino-phthalides. Besides, an unprecedented synthesis of a-acetoaryl or a-alkynyl [5,5]-oxaspirolactones has been demonstrated by employing 4-pentyn-1-ols (possessing an internal alkyne) as an annulation partner, which proceeds through a divergent [2 + 3]-annulation pathway.

1 aKambale, Digambar, A.1 aBorade, Balasaheb, R.1 aVinodkumar, Ramavath1 aKontham, Ravindar uhttp://library.ncl.res.in/content/divergent-synthesis-oxepino-phthalides-and-55-oxaspirolactones-through-222-and-23-annulation01756nas a2200193 4500008004100000022001400041245011600055210006900171260000800240300001600248490000600264520104300270100002701313700002601340700002601366700003001392700002201422856011801444 2023 eng d a2470-134300aMetabolites from lactococcus lactis subsp. lactis: isolation, structure elucidation, and antimicrobial activity0 aMetabolites from lactococcus lactis subsp lactis isolation struc cSEP a36628-366350 v83 a

Herein, we disclose the identification of novel metabolites from a potential probiotic strain, Lactococcus lactis subsp. lactis, obtained from traditional dairy milk samples collected in Maharashtra, India (in January 2021). Isolated metabolites include pyrazin-2-carboxamide [1, pyrazinamide, a potential antitubercular drug], 3,5-dihydroxy-6-methyl-2,3-dihydro-4H-pyran-4-one (2, DDMP), 2,4-di-tert-butylphenol (3), and hexadecanoic acid (4, palmitic acid). The chemical structures of these metabolites were elucidated through extensive 1D NMR (H-1 and C-13) and 2D NMR (HSQC, HMBC, and NOESY) analyses, high-resolution mass spectrometry, high-performance liquid chromatography, and single-crystal X-ray crystallography. Furthermore, these novel metabolites exhibited potent inhibitory activities against various bacteria, fungi, and yeast strains with minimum inhibitory concentrations ranging between 1.56 and 25 mu g/mL, and compounds 1 and 3 were found to be most active against a wide range of microbial strains tested.

1 aNavale, Vishwambar, D.1 aBorade, Balasaheb, R.1 aKrishna, Gamidi, Rama1 aVamkudoth, Koteswara, Rao1 aKontham, Ravindar uhttp://library.ncl.res.in/content/metabolites-lactococcus-lactis-subsp-lactis-isolation-structure-elucidation-and