• ALLA SIVA REDDY

      Articles written in Journal of Chemical Sciences

    • New reactions of allenes, alkynes, ynamides, enynones and isothiocyanates

      K C KUMARA SWAMY G GANGADHARARAO MANDALA ANITHA A LEELA SIVAKUMARI ALLA SIVA REDDY ADULA KALYANI SRINIVASARAO ALLU

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      Abstract. This perspective article is related to transformations (both catalytic and non-catalytic) involving allenes, alkynes/enynones/ynamides and isothiocyanates. Part of the work from the author’s group has been reviewed along with some new reactions of (i) allenylphosphonate/allenylphosphine oxide and (ii) a P(III) isothiocyanate. Thus, the allenylphosphine oxide Ph2P(O)C(Ph)=C=CH2 undergoes base (DBU) catalyzed addition to the β-ketophosphonate (OCH2CMe2CH2O)P(O)CH2C(O)CH3 at 90°C to afford the addition product Ph2P(O)C(Ph)=C(Me)CH[C(O)Me][P(O)(OCH2CMe2CH2O)]. In an analogous reaction, with DBU as the base at 140°C, isomeric vinylphosphine oxides (Z)-Ph2P(O)C(Ph)=C(Me)CH2[C(O)Me] and (E)-Ph2P(O)C(Ph)=C(Me)CH2[C(O)Me] were isolated. The E-isomer has been characterized by single crystal X-ray structure determination. In another set of studies, the reaction of P(III) isothiocyanate (OCH2CMe2CH2O)P(NCS) with N-(2-bromomethyl)sulfonamide afforded an unusual product with the formula(OCH2CMe2CH2O)P(O)SCH2CH2NHS(O)2-(C6H4-4-Me) as shown by X-ray structure determination. This result is different from that obtained in the recently reported analogous reaction using phenyl isothiocyanate.

    • Reactivity of ynamides with AlCl3 and ICl: Ready access to (E)-achloroenamides and (E/Z)-a-chloro-b-iodo-enamides

      ALLA SIVA REDDY MANDALA ANITHA SURAJ K C KUMARA SWAMY

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      AlCl3 acts as a chlorinating agent for ynamides in the presence of stoichiometric amount of water in the environmentally benign solvent dimethylcarbonate, affording efficient access to (E)-a-chloroenamides via hydrochlorination, with water as a protic source. The role of water in the reaction was proven by deuterium labelling experiment. Epoxy-ynamides undergo iodochlorination in addition to the cleavage of the epoxy ring to afford (E/Z)-a-chloro-b-iodo-enamides. Regio- and stereochemical assignments for the products are based on X-ray crystallographic studies.

      Chloroenamides are formed regio- and stereo-specifically via hydrochlorination of ynamides with AlCl3+H2O (1:1) in a dimethyl carbonate; aryl substituted epoxy ynamides afford (iodo)(chloro) enamides upon treatment with ICl.

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