We describe a 28 year old male with a pseudodicentric Y chromosome who suffered from azoospermia attributed to maturation arrest of the primary spermatocyte, as diagnosed by testicular biopsy. Chromosome analysis, using G, Q and C banding techniques, revealed an abnormal karyotype of 45,X[7]/46,X,psu dic (Y)(pter-->q11.2::q11.2-->pter)[33]. Polymerase chain reaction (PCR) DNA analysis did not detect the absence of DAZ and RBM1 which are candidates for azoospermic factor (AZF) genes. Therefore, it is suggested that the maturation arrest of the primary spermatocyte in this patient was caused either by a pairing dysfunction between the X and Y chromosomes during meiosis or by deletions in the autosomal or the Y chromosomal spermatogenesis controlling genes, excluding DAZ and RBM1.
Optically active cyclic xanthate was prepared by the reaction of an epoxy alcohol with NaH and CS2, and was found to be a useful intermediate for synthesis of 4-thio-2-deoxyri bose and 4'-thio-2'-deoxyribonucleoside.Since optically active epoxy alcohols have been obtained easily by the asymmetric epoxidation of allylic alcoho1,l regioand stereo-specific ring opening reactions to 2,3-epoxy alcohol by various types of nucleophiles, intramolecularly2 or intermolecularly ,3 have provided useful synthetic tools as an optically active form.4We now report a novel ring opening reaction of optically active epoxy alcohol by xanthate anion to give a-hydroxy cyclic xanthate, which provides a new method to introduce sulphur functions to epoxy alcohols, for example 2-mercapto-1,3-diols and a-hydroxyepisulphides, as optically active forms. Synthesis of 4-thio-2-deoxyribose was accomplished using this methodology.The Sharpless epoxidation of cis-allylic alcohol 1 was carried out by the reaction of (+)-diethy1 tartrate, Ti(OPri)4 and But02H to give epoxy alcohol 21-in 80% yield with 95% e.e.$ Treatment of 2 with NaH or KH in CS2 and tetrahydrofuran (THF) (1 : 2) at -78 "C, followed by warming up the reaction to -30 "C for 30 min gave cyclic xanthate 3 in 73% yield as a single stereoisomer. This stereospecific reaction involves initial formation of a sodium or potassium xanthate anion followed by the epoxide ring opening from the back side of the epoxide in a 5-exo-tetragonal fashion. Silylation of secondary alcohol 3 with trimethylsilyl trifluoromethane-sulphonate (TMSOTf) gave silyl ether 4 in 79% yield. Then the following four steps from 4, (i) reductive hydrogenolysis with LiAlH4; (ii) acetylation by Ac2O in pyridine; (iii) desilylation with Bun4NF; (iv) acetylation by Ac20 in pyridine, afforded triacetate 5 ([aID24 +6.1", c 1.0, chloroform) in 35% yield. However, the kinetic resolution1 of allylic alcohol 6 with (+)-diethy1 tartrate, Ti(0P1-i)~ and 1 2
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