Question

Hi guys, can anyone answer this question? Explain the following reactions in term of Baldwins rules and indicate why each reaction does or does not occur in terms of geometrical constraints and the orbitals involved.

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10.) Baldwin's Rules for ring closure summarise the stereoelectronic and geometric constraints on ring closure reactions. (If you want to see the original paper see J. Chem. Soc. Chemical Communications, 1976, pp 734 - 741). Explain the following reactions in term of Baldwin's rules and indicate why each reaction does or doesn't occur in term of geometrical constraints and the orbitals involved. NaoMe O НО HO NaoMe BUT Ph Ph ph Y*-**** * . $ CO2Me NaOme Na Ome CH2 CO2Me OH BUT CO2Me NaOME CO2Me SH

Answer 1

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Baldwin's Rule: Ho- Naome are favourced. orbitals, one of the and reaction become It All endo-dig a cyclizations In allone, there are two on the plane of new sing But Xo Naone orbital feasible. lie HOL * X 5- endo-trig is disfavoured. 12 •come 4 Naone X Naone "OH come wo 5- exo-trig is favoured. is disfavoured 5-endo-trig But co the Naone "st - S T c-s bond is atom is important orbital. longer, for the empty 3d initial interaction orbital of with c=c