Dearomatization of electron poor six-membered N-heterocycles through [3 + 2] annulation with aminocyclopropanes.

Many abundant and highly bioactive natural alkaloids contain an indolizidine skeleton. A simple, high yielding method to synthesize this scaffold from N-heterocycles was developed. A wide range of pyridines, quinolines and isoquinolines reacted with donor-acceptor (DA)-aminocyclopropanes via an ytterbium(iii) catalyzed [3 + 2] annulation reaction to give tetrahydroindolizine derivatives. The products were obtained with high diastereoselectivities (dr > 20 : 1) as anti-isomers. Additionally, the formed aminals could be easily converted into secondary and tertiary amines through iminium formation followed by reduction or nucleophile addition. This transformation constitutes the first example of dearomatization of electron-poor six-membered heterocycles via [3 + 2] annulation with DA cyclopropanes.

Tetrahydroquinolines via Stereospecific [3 + 3]-Annulation of Donor-Acceptor Cyclopropanes with Nitrosoarenes.

A stereospecific [3 + 3]-annulation of donor-acceptor cyclopropanes with nitrosoarenes under the influence of MgBr2 as a stoichiometric Lewis acid and reagent offers a novel approach to various structurally diverse C-8-brominated tetrahydroquinolines. In these cascades C-C, C-N, and C-Br bonds are formed. The reactions are easy to conduct and proceed under mild conditions, and the products can readily be further functionalized, rendering the method highly valuable.

Ortho-Trialkylstannyl Arylphosphanes by C-P and C-Sn Bond Formation in Arynes.

A novel and efficient approach to ortho-trialkylstannyl arylphosphanes by the reaction of arynes generated in situ with stannylated phosphanes (R3Sn-PR2) is described. Concurrent C-P and C-Sn bond formation occurs with high yields, and stannylated products are easily transformed into valuable ortho-substituted arylphosphanes. The reaction features high efficiency, good regioselectivity, and excellent practicality.

Indian plant germplasm on the global platter: an analysis.

Food security is a global concern amongst scientists, researchers and policy makers. No country is self-sufficient to address food security issues independently as almost all countries are inter-dependent for availability of plant genetic resources (PGR) in their national crop improvement programmes. Consultative Group of International Agricultural Research (CGIAR; in short CG) centres play an important role in conserving and distributing PGR through their genebanks. CG genebanks assembled the germplasm through collecting missions and acquisition the same from national genebanks of other countries. Using the Genesys Global Portal on Plant Genetic Resources, the World Information and Early Warning System (WIEWS) on Plant Genetic Resources for Food and Agriculture and other relevant databases, we analysed the conservation status of Indian-origin PGR accessions (both cultivated and wild forms possessed by India) in CG genebanks and other national genebanks, including the United States Department of Agriculture (USDA) genebanks, which can be considered as an indicator of Indian contribution to the global germplasm collection. A total of 28,027,770 accessions are being conserved world-wide by 446 organizations represented in Genesys; of these, 3.78% (100,607) are Indian-origin accessions. Similarly, 62,920 Indian-origin accessions (8.73%) have been conserved in CG genebanks which are accessible to the global research community for utilization in their respective crop improvement programmes. A total of 60 genebanks including 11 CG genebanks have deposited 824,625 accessions of PGR in the Svalbard Global Seed Vault (SGSV) as safety duplicates; the average number of accessions deposited by each genebank is 13,744, and amongst them there are 66,339 Indian-origin accessions. In principle, India has contributed 4.85 times the number of germplasm accessions to SGSV, in comparison to the mean value (13,744) of any individual genebank including CG genebanks. More importantly, about 50% of the Indian-origin accessions deposited in SGSV are traditional varieties or landraces with defined traits which form the backbone of any crop gene pool. This paper is also attempting to correlate the global data on Indian-origin germplasm with the national germplasm export profile. The analysis from this paper is discussed with the perspective of possible implications in the access and benefit sharing regime of both the International Treaty on Plant Genetic Resources for Food and Agriculture and the newly enforced Nagoya Protocol under the Convention on Biological Diversity.

An efficient approach to chiral allyloxyamines by stereospecific allylation of nitrosoarenes with chiral allylboronates.

A novel and efficient approach to allyloxyamines by the allylation of nitrosoarenes with α-chiral allylboronates is described. C-O bond formation occurs with high stereospecificity and the product allyloxyamines are easily transformed into valuable chiral building blocks such as isoxazolidines and allylic alcohols. The reaction features complete regioselectivity (O-selectivity), high E/Z selectivity, and excellent chirality transfer.

Stereospecific formal [3+2] dipolar cycloaddition of cyclopropanes with nitrosoarenes: an approach to isoxazolidines.

The MgBr2-catalyzed formal [3+2] cycloaddition of donor-acceptor activated cyclopropanes with nitrosoarenes offers a novel approach to various structurally diverse isoxazolidines. The reactions, which are experimentally easy to conduct, occur with complete stereospecificity and perfect control of regioselectivity. Product isoxazolidines can be readily transformed into α-amino lactones by reductive or decarboxylative N-O cleavage and subsequent lactonisation, and the N-aryl bond cleavage is also possible under oxidative conditions.