Unsaturated Sugars: Syntheses and Applications. A Special Issue in Honour of Professor Kalpattu Kuppuswamy Balsubramanian

Kalpattu Kuppuswamy Balsubramanian (popularly and affectionately addressed as KKB) was born on September 5th 1939, at Mylapore, Madras (now Chennai), Tamil Nadu, India, in a family gifted with tradition in the noble profession of teaching.[...]

During his illustrious research career, Prof. Balasubramanian and his co-workers have made significant contributions in the area of molecular rearrangements (especially the Claisen and Cope ones), radical chemistry, carbohydrate chemistry, electrochemistry, photochemistry and synthesis of natural products, etc. In all his research contributions have resulted in about 150 publications in reputed international journals and some selected significant contributions from his group are described in more detail below:

Molecular rearrangements
KKB's passion for molecular rearrangements (especially the Claisen rearrangement) started during his Ph.D. days and continued until his retirement. One of his earlier accomplishments was the Claisen rearrangement of bispropargyl ethers and propargyl thiobenzimidazoles [1]. He has also made significant contributions to the synthesis of coumarins, chromenes and their derivatives using Claisen rearrangements [2]. An important discovery was the fact that ethylene glycol has a remarkable effect on the rates of Claisen rearrangements of aryl propargyl ethers [3]. His group was also the first one to report an aromatic Claisen rearrangement in carbohydrates and to notice a remarkable reversal in the reactivity of anomeric aryl glycosides towards Claisen rearrangements [4].

Radical Chemistry
KKB's most significant contribution in the area of radical chemistry, among others, is the synthesis of pterocarpans by radical cyclization, which was perhaps the very first report of a radical cyclization proceeding through a disfavoured 5-endo-trig process [5]. His group has also developed a radical route for the stereoselective synthesis of C-glycosides [6].

Carbohydrate Chemistry
KKB's most significant contribution in the area of carbohydrate chemistry is the synthesis of 2-Cformyl glycals using the Vilsmeier-Haack reaction [9]. This procedure is being followed world-wide by several groups for the synthesis and applications of 2-C-formyl glycals [9]. His group has developed a carbohydrate based route to optically active furano[2,3-b]benzofuran system, a key feature present in aflatoxins [10]. His research towards developing a better catalyst for the Ferrier rearrangement in carbohydrates has resulted in the finding that InCl 3 is the best suited for this reaction [11]. Subsequently, several other groups have used InCl 3 to carry out this rearrangement. His group was also one among the first to report the use of microwaves in carbohydrate chemistry [12].

Electrochemistry
Balasubramanian's contributions towards the use of electric current to bring about organic transformations is quite remarkable. He has used electrochemistry to synthesize compounds that are not generally attainable by conventional methods. Notable among these are his synthesis and isolation of o-allenylphenols and selective reduction of bromine in the presence of an epoxide functional group [13]. Apart from these areas, his group has also contributed significantly towards the synthesis and reactions of allenes [14], flavanoids [15], chromenes [16], indoles [17], etc.

Professor Balasubramanian: Mentor, Teacher and Recognized Scientist
Balasubramanian has guided about 30 students for their Ph.D. degree all of whom are well settled and well placed in multinational companies as well as in reputed academic institutes both in India and abroad. He has always been admired by students as one of the best teachers of his time at IIT-Chennai. His many noteworthy research contributions have been recognized both nationally and internationally. At the national level, he is an honorary fellow of the Indian Academy of Sciences, and the Indian National Science Academy, and he has delivered several endowment lectures and special lectures at various educational institutions in India. Internationally, he has been an Alexander van Humboldt (AvH) Foundation Fellow (1984-84), and Senior AvH Visiting Fellow (1997), a Guest Scientist at the National Institute of Standards and Technology, Gaithersburg, USA (1994), Visiting Professor at the University of Nancy (1984) and INSA-JSPS Visiting Fellow to Japan (2000). He has also visited several universities in the USA, UK, Germany, The Netherlands, France, Japan, and Switzerland to deliver special lectures. On the personal side, Balasubramanian has enjoyed a long and happy married life with his wife Mrs. Chandra. His only son, a mechanical engineering graduate from IIT-Madras, Chennai, is currently pursuing his postdoctoral research at NIST, Gaithersburg, USA. Balasubramanian is also noted for his fondness of South Indian classical music.
It is our pleasure and honour to guest-edit a special issue of Molecules on the topic of Unsaturated Sugars: Syntheses and Applications, with manuscripts contributed by distinguished scientists from all over the world working in the area. The issue is dedicated to Professor K.K. Balasubramanian on the occasion of his 65 th birth anniversary.