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1,1‐Difluoro‐benzocyclopropene (1) ionizes in fluorosulphonic acid to yield the cation 2, which is stable at − 50° for several hours. Upon quenching with water 2 affords benzoic acid.

Most severe episodes of neonatal alloimmune thrombocytopenic purpura (NATP) are caused by antiplatelet alloantibodies against the HPA-1a (PlA1) antigen. However, half of subsequent fetuses produced from a HPA-1a/b father (genotypic frequency 28%) will result in a child who is not affected. Some investigators manage NATP by confirming the fetal platelet phenotype using percutaneous umbilical cord sampling, a procedure that carries a low but real risk of fetal morbidity and mortality. More recently, physicians determine the fetal platelet antigen genotype using DNA derived from amniotic fluid or chorionic villus samples. All therapy is withdrawn for a fetus who genotypes as HPA-1b/b. However, since the fetus is the same genotype as the mother, there can be uncertainty about the origin of the genetic material and thus the validity of the fetal genotype. The inappropriate withdrawal of therapy for a erroneously genotyped fetus could be fatal, and consequently many physicians advocate fetal HPA-1 phenotyping with confirmation using percutaneous umbilical blood sampling. In this report we describe the management of two pregnancies with previously affected infants due to anti-HPA-1a alloantibodies. Both husbands were HPA-1a/b. For the current pregnancies, amniotic fluid was collected at 20 or 29 weeks of gestation, and the platelet genotype indicated that the fetuses were HPA-1b/b. The fetal origin of the amniotic fluid derived DNA was confirmed by the forensic technique of DNA profiling using variable number of tandem repeat (VNTR) analysis. All therapy was withdrawn, percutaneous umbilical blood sampling was not performed, and both women vaginally delivered healthy non-thrombocytopenic infants. The application of platelet alloantigen genotyping using DNA from amniotic fluid cells identified the HPA-1b/b fetus, and VNTR analysis confirmed that the tissue was fetal derived, thus avoiding the necessity for percutaneous umbilical blood sampling. The use of this approach in patients at risk will avoid additional investigation and treatment in approximately one-seventh of all NATP pregnancies involving the HPA-1a antigen.

Ceric ammonium nitrate in 70% aqueous acetonitrile oxidizes 5-phenyl-1-pentanol and 4-phenyl-1-butanol to 2-benzyl-and 2-phenyltetrahydrofuran, respectively. Competing processes include benzylic oxidation leading to ketone formation and to oxidative cleavage products. The effects on tetrahydrofuran formation by changing the cerium concentration and by varying the solvent are given. Oxidation of 3-phenyl-1-propanol yields chromanone as the only major reaction product when 2 equiv of ceric ammonium nitrate is employed. Chromanone is oxidized to chromone when >2 equiv of the oxidant is used. The mechanistic implications of these results are discussed.Cerium(1V) oxidations of primary alcohols, unlike those of benzylic,2 cyclopropylcarbinyl,3 or certain secondary alc o h o l~,~ yield tetrahydrofuran derivatives. Tetrahydrofuran formation represents but one of the three modes of reaction identified with cerium(1V) oxidations of alcohols, the others being oxidative cleavage resulting in substrate fragmentation and a-carbon-hydrogen cleavage yielding aldehydes or ket0nes.j Trahanovsky, Young, and Nave have studied the oxidation of 1-pentanol by ceric ammonium nitrate (CAN) and found 2-methyltetrahydrofuran as the only isolable reaction product.6 Although the similarity of this reaction to that of the corresponding lead tetraacetate oxidation7 has been pointed out, the synthetic utility and mechanistic course of cerium(1V) oxidations of primary alcohols have not been further documented.Phenyl-substituted alkanols have been used previously to determine the effect of the phenyl group on the course of lead tetraacetate oxidations.s The phenyl label is useful for identifying the hydrogen transfer step and for determining its specificity in reactions of alcohols with one-electron oxidants.Results 6-Phenyl-1-pentanol. Oxidation of 5-phenyl-1-pentanol (10 mmol) by ceric ammonium nitrate (20 mmol) in 25 ml of 70% aqueous acetonitrile at 75' afforded 2-benzyltetrahydrofuran (1) and benzoic acid as the only major identifiable reaction products (eq 1). Two other products, tentatively identified as benzaldehyde and 5-phenyl-1-pentyl nitrate, were observed by GLC analysis but in combined amounts of less than 8%; unreacted alcohol, by far the major constituent of the reaction mixture (77%), was also identified. The yield of 1, based on reacted 5-phenyl-1-pentanol, was 40%; benzoic acid was formed in less than 10% yield. CAN

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