With the current changes in the Spring Boot 1.2.0 snapshot version, the autoconfiguration for Hibernate depends on classes and packages which were changed in Hibernate 4.3. So with Hibernate 4.2 at the moment you will get NoClassDefFoundErrors when using the Hibernate autoconfiguration (and, when my pull request is accepted, the autoconfiguration will be disabled for Hibernate 4.2).

As a workaround, you can either create manually the whole Hibernate and JPA configuration beans, or copy and modify the source of the class org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration. The code, which relies on Hibernate 4.3 specific classes is at the moment solely contained in the method customizeVendorProperties:

@Override
protected void customizeVendorProperties(Map<String, Object> vendorProperties) {
    super.customizeVendorProperties(vendorProperties);
    if (!vendorProperties.containsKey(JTA_PLATFORM)) {
        JtaTransactionManager jtaTransactionManager = getJtaTransactionManager();
        if (jtaTransactionManager != null) {
            vendorProperties.put(JTA_PLATFORM, new SpringJtaPlatform(
                    jtaTransactionManager));
        }
        else {
            vendorProperties.put(JTA_PLATFORM, NoJtaPlatform.INSTANCE);
        }
    }
}

If you have configured the JTA platform with the property spring.jpa.properties.hibernate.transaction.jta.platform, you can just remove the complete method. Otherwise, create an instance of the JTA platform you need and put it into the vendorProperties map (but don’t use the class SpringJtaPlatform from Spring Boot, because it also depends on Hibernate 4.3)