@article {42730, title = {Hydrophosphonylation of activated alkenes and alkynes via fluoride ion activation in ionic liquid medium}, journal = {Tetrahedron}, volume = {65}, year = {2009}, month = {JUL}, pages = {7603{\textendash}7610}, abstract = {

A simple transition metal-free hydro/hydrothiophosphonylation of Baylis{\textendash}Hillman adducts, substituted allyl bromides, allenylphosphonates and alkynes, promoted by fluoride ion in ionic liquid, is described. Clear-cut evidence for fluoride activation of the phosphite via pentacoordinate phosphorus is provided for the first time. Also, in a comparative reaction, the product obtained was different from that from the palladium catalyzed one. Structures of key products are proven by X-ray crystallography.

}, doi = {10.1016/j.tet.2009.06.096}, author = {Balaraman, Ekambaram and Srinivas, Venu and Swamy, K. C. Kumara} } @article {42715, title = {Alkynyl and phosphonyl substituted nucleobases: a case of thermally induced conformational polymorphism}, journal = {Crystal Growth \& Design}, volume = {11}, year = {2011}, month = {APR}, pages = {2302{\textendash}2310}, abstract = {

Substituted nucleobases with alkynyl and phosphonyl groups were investigated in the context of supramolecular interactions and possible use toward synthesis of nucleoside phosphonic acids (NPAs). The adeninyl compound (adeninyl-N-9)-CH2CH2CH2CH2C=CH exhibits conformational polymorphism as revealed by X-ray structures determined at 200 and 298 K. Interestingly, in the compound (adeninyl-N-9)-(CH2)15CH3, the long aliphatic carbon chain does not show disorder. A rather unusual bending of alkyl chain, likely due to C{\textendash}H{\textperiodcentered}{\textperiodcentered}{\textperiodcentered}O interactions, is observed in the case of the thymine compound (thyminyl)-CH2CH2CH2C=CH that possesses a terminal alkyne group. The powerful hydrogen bond acceptor property of the phosphoryl oxygen (P=O) does not perturb (unless assisted by other hydrogen bonding partners) the homo base-pairing in the structures of most of the phosphonyl substituted nucleobases studied.

}, doi = {10.1021/cg101737x}, author = {Swamy, K. C. Kumara and Allu, Srinivasarao and Srinivas, Venu and Balaraman, Ekambaram and Kumar, K. V. P. Pavan} } @article {42714, title = {Cyclodiphosph(III)azane chemistry {\textendash} ylides from the reaction of [(RNH)P-N(t-Bu)]2 [R = t-Bu, i-Pr] with dimethyl maleate and chiral ansa-type derivatives from reaction of [ClP-N(t-Bu)]2 with a substituted BINOL}, journal = {Inorganica Chimica Acta}, volume = {372}, year = {2011}, month = {JUN}, pages = {374{\textendash}382}, abstract = {

Use of a simple inorganic ring system with the cyclodiphosph(III)azane skeleton [e.g. [(RNH)P-N(t-Bu)]2 [R = t-Bu (7), i-Pr (8)] to probe some of the intermediates proposed in phosphine mediated organic reactions is highlighted. Thus the reaction of 7{\textendash}8 with the allenylphosphine oxide Ph2P(O)C(Ph)double bond; length as m-dashCdouble bond; length as m-dashCH2 (9) affords the phosphinimines [(RNH)P(μ-N-t-Bu)2P(double bond; length as m-dashN-R)-C(double bond; length as m-dashCH2)CH(Ph)-P(O)Ph2] [R = t-Bu (10), i-Pr (11)], while a similar reaction of 7{\textendash}8 with dimethyl maleate (or dimethyl fumarate) affords the ylides [(RNH)P(μ-N-t-Bu)2P(NH-R)double bond; length as m-dashC(CO2Me)-CH2(CO2Me) [R = t-Bu (18), i-Pr (19)]. The implication of such reactions on phosphine mediated organic transformations including Morita{\textendash}Baylis{\textendash}Hillman reaction is mentioned. In a rather rare type of situation, an unusually long phosphoryl (Pdouble bond; length as m-dashO) bond [1.538 (5) {\r A}] as revealed the X-ray structure of {(R)-6,6'-(t-Bu)2-1,1'-(C10H5)2-2,2'-O2-}{P(O)(N-t-Bu)2-P(Se)} (27) is rationalized by means of crystallographic disorder in packing after comparing the data with that in the literature and {1,1'-(C10H6)2-2,2'-O2}{P(Se)(N-t-Bu)2-P(Se)} (29). X-ray structures of the new compounds 10{\textendash}11, 18{\textendash}19, 27 and 29 are discussed. Compound 10 crystallizes in the chiral space group Pca2(1) with (S)-chirality at the carbon center [{\textendash}C(double bond; length as m-dashCH2)CH(Ph)-P] suggesting a case of spontaneous resolution through crystallization.

}, doi = {10.1016/j.ica.2010.12.072}, author = {Swamy, K.C. Kumara and Gangadhararao, G. and Srinivas, Venu and Kumar, N. N. Bhuvan and Balaraman, Ekambaram and Chakravarty, Manab} }