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

  • K C Kumara SwamyEmail author
  • G Gangadhararao
  • Mandala Anitha
  • A Leela Sivakumari
  • Alla Siva Reddy
  • Adula Kalyani
  • Srinivasarao Allu
Perspective Article


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 \(\hbox {Ph}_{2}\hbox {P(O)C(Ph)=C=CH}_{2}\) undergoes base (DBU) catalyzed addition to the \(\beta \)-ketophosphonate \(\hbox {(OCH}_{2}\hbox {CMe}_{2}\hbox {CH}_{2}\hbox {O)P(O)CH}_{2}\hbox {C(O)CH}_{3}\) at \(90\,{^{\circ }}\hbox {C}\) to afford the addition product \(\hbox {Ph}_{2}\hbox {P(O)C(Ph)=C(Me)CH[C(O)Me][P(O)(OCH}_{2}\hbox {CMe}_{2}\hbox {CH}_{2}\hbox {O)]}\). In an analogous reaction, with DBU as the base at \(140\;{^{\circ }}\hbox {C}\), isomeric vinylphosphine oxides (Z)-\(\hbox {Ph}_{2}\hbox {P(O)C(Ph)=C(Me)CH}_{2}\hbox {[C(O)Me]}\) and (E)-\(\hbox {Ph}_{2}\hbox {P(O)C(Ph)=C(Me)CH}_{2}\hbox {[C(O)Me]}\) 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 \(\hbox {(OCH}_{2}\hbox {CMe}_{2}\hbox {CH}_{2}\hbox {O)P(NCS)}\) with N-(2-bromomethyl)sulfonamide afforded an unusual product with the formula \(\hbox {(OCH}_{2}\hbox {CMe}_{2}\hbox {CH}_{2}\hbox {O)P(O)SCH}_{2}\hbox {CH}_{2}\hbox {NHS(O)}_{2}\)-\((\hbox {C}_{6}\hbox {H}_{4}\)-4-\(\hbox {Me)}\) as shown by X-ray structure determination. This result is different from that obtained in the recently reported analogous reaction using phenyl isothiocyanate.

Graphical Abstract

Synopsis. Base-catalyzed the addition of \(\beta \)-ketophosphonate or ethyl acetoacetate to allenylphosphine oxide affords vinylphosphine oxides; in the latter case, elimination of the ester group also takes place. It is also shown that reactivity of a P(III) isothiocyanate is different from that of organic isothiocyanates.


Allene allenylphosphine oxide enynone ynamide P(III) isothiocyanate X-ray structure 



We thank the Department of Science and Technology (DST, New Delhi; FIST, PURSE Phase II) and the University Grants Commission (UGC, New Delhi; NRC, SAP) for financial support and equipment. KCK thanks CSIR (New Delhi for a project (02(0240)/15/EMR-II) and DST for the J. C. Bose fellowship (SR/S2/JCB-53/2010).

Supplementary material

12039_2018_1496_MOESM1_ESM.pdf (549 kb)
Supplementary material 1 (pdf 548 KB)


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Copyright information

© Indian Academy of Sciences 2018

Authors and Affiliations

  1. 1.School of ChemistryUniversity of HyderabadHyderabadIndia

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