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Since the appearance of the Russian edition of this monograph (1967), the main tendencies of the development of total synfuesis have not changed. The accelerated accumulation of experimental material is continuing, mainly in the form of the improvement of already-existing synthesis schemes. The main new advance is the development of asymmetric syn theses with intermediates that have made it possible to avoid the main dis advantage of total synthesis - the formation of racemic final compounds. The most important work that has appeared since the appearance of the Russian edition is given in an Appendix to the book. Apart from this, only a very slight rearrangement of the material and of some of the schemes has been carried out for the American edition. A. A. Akhrem Yu. A. Titov Moscow, July 1968 v Preface to the Russian Edition Steroids are one of the most interesting and most widely distributed and, at the same time, one of the most structurally complex groups of natural compounds. In spite of this, the great theoretical and practical importance of steroids for biology and medicine has led to very intensive scientific research work on their synthesis. The numerous methods for obtaining steroids developed at the present time can be divided into four main groups: isolation from natural sources, microbiological synthesis, partial synthesis from natural raw material already containing the steroid skeleton, and, finally, total chemical synthesis from precursors of com paratively simple structure.
