Koshkin, Alexei A.; Singh, Sanjay K.; Nielsen, Poul; Rajwanshi, Vivek K.; Kumar, Ravindra; Meldgaard, Michael; Olsen, Carl Erik; Wengel, Jesper Tetrahedron, 1998, vol. 54, # 14 p. 3607 - 3630 doi: 10.1016/S0040-4020(98)00094-5